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Frequently Asked Questions: Septic Systems

In Guam, the use of onsite wastewater disposal systems (commonly referred to as ”septic systems”) is regulated through a number of laws and regulations.  The Guam Environmental Protection Agency (GEPA) Administers the Toilet Facilities and Sewage Disposal Act (10 GCA Chapter 48), and its two implementing regulations: the Individual Wastewater Disposal System Regulations (22 GAR Chapter 12) and the Connection to Public Sewer Regulations (22 GAR Chapter 25).  This law and its regulations cover the specific requirements for the permitting, design and construction of septic systems in Guam.  In addition, lot size and sewer connection requirements are also incorporated into Guam’s Water Quality Standards (22 GAR Chapter 5), the Zoning Law (21 GCA Chapter 61) and the Subdivision Law (21 GCA Chapter 62).  The questions and answers below are meant to step you through the application of these various requirements to the design, permitting, and construction of a septic system for a single family dwelling.

Frequently Asked Questions: Septic Systems – January 5, 2023

  • What should I be aware of if I am buying an unsewered property?
    • Not all unsewered properties can be developed for residential use.  You must be able to legally build an onsite wastewater disposal system (“septic system”) for your proposed dwelling, otherwise you will not receive a building permit to construct. The sections below will provide detailed answers to this question, but for convenience, the primary things you should work with your realtor or the seller to determine are:
     
    • Any single one of these issues could prevent you from being able to obtain a construction permit if the relevant legal requirements are not met.  It is therefore extremely important to discuss each of these with your realtor and/or the seller, and if possible to verify on your own before committing to the purchase of a property that you might not be able to build on.
  • How do I determine if public sewer is available?
    • Horizontal distance to sewer: 200 feet.  You are not allowed to build or use a septic system if public sewer service is available.  Under Guam’s “Connection to Public Sewer Regulations” at 22 GAR Chapter 25, public sewer is considered to be available when the sewer is located in a roadway, street or easement abutting the lot on which the home will be located, and such home will be located within 200 feet (measured horizontally in a straight line) of the sewer line.
    • Vertical alignment: no more than 20 feet below existing public sewer: In addition to the horizontal distance requirement, connection to public sewer is also required even if the sewer is located at an elevation higher than your proposed home’s floor elevation, up to a limit of 20 feet. If your proposed home is located within 200 feet horizontally, and is less than 20 feet below the elevation of the existing sewer line, you are required to connect, and your connection will require the use of a pump. Exemptions to this particular requirement for new septic systems may be granted by the Administrator of GEPA under both 22 GAR §12104(c) when “by written findings it is determined that the public health and welfare will not be jeopardized.” Exemptions to this requirement for existing septic systems may also be granted the variances clauses of the Connection to Public Sewer Regulations at 22 GAR §25108(a)(2).
    • You should consult with your engineer or architect to determine whether to redesign your home to avoid the need for a pump, seek a variance, or move ahead with a pumped connection to sewer. Connection to sewer has several advantages including less long-term risk of expensive repairs, and enables a larger portion of the property to be developed (or even subdivided to allow more than a single dwelling to be built). Packaged sewage pump systems for single family homes are widely available and have been in use for decades world-wide, and have a good reputation for reliability. However, they are electrical and mechanical devices and will eventually require repair or replacement. The best solution is to design your home to have its lowest floor elevation above the elevation of the public sewer, so that a pump is not required. If you must install a pump, your engineer or architect must ensure the applicable design requirements under 22 GAR Chapter 25 are considered.
    • If sewer is not available: you may be able to construct a septic system, if all other requirements are met.
  • Is my property located above the aquifer?
    • The location of your home with respect to the Groundwater Protection Zone, or “GPZ”, determines the minimum lot size on which a new septic system may be permitted.  The current GPZ location is determined by the Department of Land Management’s Groundwater Protection Zone Overlay Map, which was last approved in 1997.  The GPZ map is available for viewing here.
     
  • Is my lot size large enough to permit a septic system?
    • The answer to this question depends on whether your property is located within the Groundwater Protection Zone (“GPZ”), or outside the GPZ.  See the section above titled “Is my property located above the aquifer?” for information on how to make this determination.
    • Minimum lot size over the aquifer (within the GPZ):  19,200 square feet (1,784 square meters). Per the Zoning Law at 21 GCA §61501(c), lot sizes above the aquifer are established by the Guam Environmental Protection Agency (GEPA).  The Guam Water Quality Standards at 22 GAR §5101(c)(1)(B) requires that “high-density residential development, more than one (1) dwelling per one-half (1/2) acre, should not occur without adequate public sewer service.”  GEPA implemented this requirement through the establishment of minimum lot sizes, based on the existing requirements of the Zoning and Subdivision Laws.  Within the aquifer, as mapped by the Department of Land Management in 1997 in their Groundwater Protection Zone (GPZ) Overlay, the minimum residential lot size on which a septic system may be constructed (for a single dwelling unit) is 19,200 square feet (1,784 square meters), or approximately one-half acre, based on 21 GCA §61501(a). See GEPA minimum lot size determination Memoranda here:  1997 & 2009
    • GEPA’s prior determinations for minimum lot sizes over the aquifer included an allowance for a smaller size of 9,600 square feet (892 square meters) for lots subdivided under the Zoning Law’s “Parental Division of Property” clause at 21 GCA §62140(b).  This exception to the half-acre requirement of the Guam Water Quality Standards is currently under legal review.
    • Minimum lot sizes outside the aquifer (outside the GPZ): 10,000 square feet (929 square meters).  Outside the aquifer, as mapped by the Department of Land Management in 1997 in their Groundwater Protection Zone (GPZ) Overlay, the minimum residential lot size on which a septic system may be constructed (for a single dwelling unit) is determined by Guam’s Zoning and Subdivision Laws, but generally speaking is not less than 10,000 square feet (929 square meters), based on 21 GCA §61501(a) and 21 GCA §62105(a).  See GEPA minimum lot size determination Memoranda here:  1997 & 2009
    • As with the lot sizes inside the aquifer, GEPA’s prior listing of minimum lot sizes outside the aquifer included an allowance for a smaller size of 9,600 square feet (892 square meters) for lots subdivided under the Zoning Law’s “Parental Division of Property” clause at 21 GCA §62140(b).
  • What about distances to the shoreline, wells, or other water features?
    • Distance from wells, “Waters of the Territory”, and other things:  Both the Guam Toilet Facilities and Sewage Disposal System Act (10 GCA Chapter 48) and Guam’s Individual Wastewater Disposal System Regulations (22 GAR Chapter 12), do not allow the construction of any component of a septic system within the distances shown in Table I below.
    • The most important distances from this table to consider when planning construction of a new home are the distances to wells, and the distances to “Waters of the Territory”, which by definition include all shore waters surrounding Guam, plus streams, lakes, springs, and wetlands.  No new septic system will be permitted by GEPA within the 300 foot setback distance from these water features.  This should be one of the first things checked when purchasing a property or making the decision to build a home.
    • Distances from property lines and buildings should be accounted for during the design of your home by the engineer or architect in responsible charge of the design work.  As long as minimum lot sizes are met, meeting these requirements should not be a problem.
    Table I: Minimum Safe Horizontal Distances in Feet
    From:To:
    Septic TankAbsorption Bed (Leaching Field)Absorption Trench
    Any Water of the Territory300 ft300 ft300 ft
    Wells300 ft300 ft300 ft
    Any building (including your home)10 ft20 ft20 ft
    Property boundary lines5 ft5 ft5 ft
    Water lines10 ft25 ft25 ft
    The following illustration is from the original print edition of the Individual Wastewater Disposal Regulations and provides a helpful illustration of the application of these setback distances:
  • What if my property is located within a Flood Zone?
    • Per the Guam Individual Wastewater Disposal System Regulations at 22 GAR §12105(h),new septic systems shall not be permitted within flood hazard areas. New buildings in these areas must be connected to public sewer.  You can view the latest Flood Hazard Areas designated for Guam on the Federal Emergency Management Agency’s (FEMA’s) Flood Rate Insurance Map (FIRM) viewer here: https://msc.fema.gov/nfhl
  • What do I need to know about soil conditions? Do I need a percolation test?
    • The short answer to this is that a percolation test should be performed for every proposed new septic system, as well as a deeper observation pit to check for the presence of conditions below the proposed absorption bed that might make construction of a septic system impossible, or cause an early failure.
    • Not all soils in Guam are suitable for septic systems.  Guam’s regulations set a minimum percolation rate of 1 inch in 60 minutes, below which a septic system may not be constructed.  Percolation rates between that value and 1 inch in 30 minutes must be constructed using a trench system, as opposed to a bed (“leaching field”), which requires more space but makes better use of the slower-percolating soils to ensure the septic system provides a reasonable service life.
    • Southern Guam is particularly prone to low percolation-rate soils, due to its volcanic origins compared to the limestone plateau of Northern Guam, which in general is more forgiving, but there are also regions of volcanic geology within Northern Guam, as well as pockets of deep, clayey soils which are not as favorable for septic system construction.  It is therefore strongly recommended to perform a percolation test prior to designing a septic system, no matter where in Guam you will be building.
    • In addition to the percolation test, which uses a small hole dug only to the depth of the proposed absorption system, a deeper observation pit should be dug for the purpose of identifying impermeable rock layers or signs of locally high water tables, both of which will prevent a septic system from functioning.  Impermeable rock layers can sometimes be found near the surface in areas of volcanic geology, and will prevent the proper percolation of wastewater from the absorption system, often resulting in surfacing of wastewater down-hill of the septic system, and inability to accept wastewater during wet conditions.
    • The presence of groundwater less than 3 to 5 feet of the bottom of an absorption system will result in similar failures of the septic system.  High water-table conditions typically occur at lower elevations, flood plans, or near streams and wetlands, but may occur anywhere and can be detected by an experienced soil evaluator through either the direct observation of standing water within the observation pit, or through discoloration of soils indicating occasional periods of prolonged saturation, which may not occur all the time, but will prevent a septic system from working during certain parts of the year.
    • Be cautious:  It may be tempting to request additional percolation tests or soil evaluations if the results show that a site will not be suitable for a septic system.  It is very possible that you may obtain a different result from a site located on a different portion of your property indicating a septic system may be feasible.  It is natural for a prospective homeowner to want to reject what seems like bad news in favor of better results from a second test.  But this can lead to disappointment or even misery, in the case that a septic system fails and the building plumbing cannot be used.  Ensure that you work closely with your engineer or architect in such a situation, and be realistic about your expectations.  The unfavorable test result was most likely a true representation of that portion of your property, and a more favorable test result obtained from another portion should be viewed with caution, and at most, the final design should be based on the average of all test results, not just the most favorable.  Be especially cautious if there are also indications the soils may be saturated with water within 3 feet of the absorption trench bottom, or that the site receives stormwater runoff from nearby areas.  These factors, on their own or especially in combination with a low measured percolation rate, should serve as a serious warning.
  • How much space will be left for me to build a house after I fit in the required septic system?
    • It’s important to realize that Guam’s Individual Wastewater Disposal System Regulations requires that you also set aside adequate space for a replacement absorption system (leaching field or trench) of the same size as required for initial construction.  This is to ensure that you are able to recover in the event of a failed septic system, which is always a difficult (and expensive) situation, but can be considerably worse if space is not available for replacement.  Your engineer or architect will take this into consideration when designing your home, along with other requirements such as parking and setbacks from property lines required under other Guam laws and regulations.
    • As long as your property meets the minimum lot size requirements and the soils are favorable for a septic system, there should be no problem fitting a reasonably sized home alongside the required septic system components and setbacks.
  • Who is responsible for determining compliance with all of these requirements?
    • The answer to this question depends on the stage of development.  If you are interested in purchasing a property, you should work with your realtor to disclose known conditions that may restrict the installation of a septic system, in addition to doing your own basic research to make sure the property location does not trigger any of the septic system setbacks or prohibitions set by law and regulation.
    • If you have a property and are interested in building a home, you can use publicly available information, as linked to above and in the Additional Resources section of this FAQ, to determine the basic suitability of your lot for construction, based on location, lot size, and proximity to protected features.
    • If you are in the process of designing your home, your engineer or architect is responsible for all aspects of the design of your home to ensure it meets relevant government requirements, and this includes the requirements for septic systems described in this document.  Your engineer or architect should review your property information and location as a first step, to determine whether there are any immediate indications that a septic system permit may not be granted, such as a lot size or setback issue.  If there are, the engineer or architect should inform you right away, to ensure you do not knowingly proceed with expensive design work that might not lead to a construction permit.  If the basic site suitability requirements are met, and prior to the start of design work, the engineer or architect should then arrange for the percolation test and soil observation pit, and should personally observe the test and interpret the results to determine whether a septic system is feasible.  If it is not, they should inform you immediately and discuss alternatives, before proceeding with a design or billing you for additional work that may not lead to a permit.
    • If you already have a design and are working to obtain a permit with your contractor as your agent, and depending on the terms of your contract, your contractor may responsible for obtaining all of the relevant design information from your engineer or architect, submitting this information with the permit application, and working with GEPA to make changes or modifications, as necessary.  Delays during the permitting process are to be expected if the contractor fails to submit all of the relevant engineering documentation, or if the engineer or architect fails to follow the required site assessment or design requirements.
    • Once your septic system is built and you have occupied your new home, you become responsible for the long-term operation and maintenance, as well as repairs or replacements in the event the leaching field (or trench) system fails.
  • What are my options if a septic system is not allowed?
    • The Guam Toilet Facilities and Sewage Disposal System at 10 GCA Chapter 48 allow for only two methods of wastewater disposal for any building, including single family dwellings: connection to public sewer, or connection to an approved septic system.  Other alternatives that are sometimes used in other places, such as holding tanks, are not currently allowed under Guam law.  Therefore if public sewer is not available, and a septic system may not be permitted in accordance with Guam’s laws and regulations, another land use that does not require a building served with piped water may be allowable, depending on Zoning and other requirements.
  • If my permit is denied, is there an appeal process?
    • The Individual Wastewater Disposal System Regulations at 22 GAR §12105(k) provides for the ability for anyone who is denied a permit to request a hearing before the GEPA Board of Directors, which shall affirm, modify, or revoke the denial, or issue the permit on the basis of evidence presented at the hearing.  Such request must be filed in writing within 15 days of the official notification of denial by GEPA.
  • Are other types of buildings allowed to be connected to a septic system?
    • Within the aquifer (as defined by the GPZ), the only building types that may be served with a septic system are single family dwellings and duplexes, based on the combined requirements of the Guam Water Quality Standards (22 GAR Chapter 5) and the Individual Wastewater Disposal System Regulations (22 Gar Chapter 12).
     
    • Outside the aquifer, other building types may be served with septic systems, but in no case may anything other than “domestic wastewater” be disposed of on-site.  Domestic wastewater refers to wastes coming only domestic-type sources such as toilets and sinks.  Guam’s Water Quality Standards effectively prevent the disposal of wastewaters generated by industrial or other commercial uses, all of which could reasonably be expected to exceed groundwater quality criteria for land disposal, which are based on drinking water standards, even outside the aquifer.
     
    • In addition, the Guam Regulations provide design criteria only for septic tanks associated with single family dwellings, duplexes, and apartments up to a maximum of four units.  The design of onsite wastewater disposal systems any other type of building must be based on engineering methods approved by GEPA on a case-by-case basis, and effluent from such systems must meet Guam Water Quality Standards criteria.
  • Can I add a bedroom or bathroom if my house is on a septic system?
    • Generally speaking, unless your septic system was designed with additional capacity, any addition to your home will require modification or replacement of your septic tank and/or soil absorption system (leaching field or trench).  Additions to a home served by a septic system must be reviewed and approved by the GEPA Water Pollution Control Program and Chief Engineer, as part of a DPW Building Permit Application.  You should coordinate with GEPA as early as possible if planning an addition, and have your engineer or architect discuss the situation with GEPA staff to determine if percolation tests will be required.  Make sure to find your “as-built” drawings showing the dimensions of your existing septic system for review during the design process.  If you can’t find these drawings, it is more likely that a new leaching field will be required to ensure you have adequate soil absorption area for the planned addition.
     
    • Additions to a home that do not increase the number of bedrooms (for example a kitchen remodel, an office, or a new living room) do not require modification of the existing septic system.
     
    • Keep in mind, also, that no addition may be built on top of a septic tank or leaching field, and the 10 foot setback from the building to the septic tank and 20 foot setback to the soil absorption system must be maintained.  In addition, the 100% reserve leaching field area and its setbacks must be preserved to account for the possibility of future system failure.  On a small lot, this may impose a significant limit on the size of any proposed addition.
     
    • If you do not have adequate space available to re-size your septic tank and soil absorption system to accommodate your proposed addition, the addition will not be permitted by GEPA pursuant to 22 GAR §12105(e) & (f).
  • Can I convert my house to a duplex if it is served by a septic system?
    • If the lot size is adequate to accommodate two dwelling units (for example, within the aquifer: 19,200 square feet x 2 = 38,400 square feet), conversion to a duplex may be permitted using a single septic system.  The septic system must be large enough to accommodate the full occupancy of the proposed duplex, which is very likely to require construction of a new septic tank and leaching field.
    • Conversion of a single family home to a duplex on a lot that is sized only for a single family dwelling will not be approved by GEPA pursuant to 22 GAR §12105(e) & (f).
  • Can I build something like a pool or shed on top of my septic system?
    • No structure may be built on top of any portion of a septic system.  A setback of 10 feet is required between any structure and the septic tank, and 20 feet between any structure and the soil absorption system.  In addition, no structure may be built within the space reserved for absorption system replacement, or within the 20 foot setback distance of that area, in accordance with 22 GAR §12105(d).
    • There are numerous reasons for this, based on both engineering and common sense.  The regulations require that the septic tank and leaching field must remain accessible for maintenance and repair, as necessary, and that no structures be built which would prevent the use of the 100% reserve absorption system in the event of a failure.  Other, more technical reasons include precautions to prevent damage to your home or dangers to life and health.  Building too close to a leaching field may cause your foundation to settle and damage your home.  Building too close to or on top of a leaching field or septic tank is also likely to result in the introduction of odors and gases to indoor spaces, which can be both hazardous to life and health, and create a risk of explosion or fire.
  • What causes a septic system to fail, and how can I tell if mine is failing?
    • A septic system most often fails because the soil absorption system (the leaching field or trench) stops accepting liquid.  This can occur due to clogging of the soil over time, or due to saturation of the surrounding soils with water from some other source (such as stormwater runoff from outside areas, or rising groundwater).
    • The symptoms of a failing septic system may include a noticeable slowing of drainage from toilets and fixtures that doesn’t go away after cleaning the pipes, and/or the “surfacing” of wastewater in your yard or nearby areas.  In extreme cases, wastewater may backflow into your home through floor drains, often while running a washing machine or some other fixture that uses a lot of water at one time.
    • “Surfacing” of wastewater is another common indicator of a septic system failure, and refers to seepage of wastewater from the ground surface.  A properly operating septic system will not result in any surface discharge of wastewater, or any odors.  Seeping wastewater will often appear near the failed septic system, or just downhill from it, especially in places where the natural ground surface has been disturbed through steep excavations or installation of retaining walls.  Seepage from a failed septic system will usually have an unpleasant odor, will cause areas of black or dark green slime, and will attract large numbers of flies.
    • Failure due to excessive stormwater runoff, a high water table, or an unforeseen layer of solid rock below the leaching field will occur fairly quickly after occupancy and is very difficult (or in some cases impossible) to fix.  This type of failure is usually the result of site conditions that were overlooked during design and construction.  This is why it is critical that the design of your home include both a percolation test and a deeper soil observation pit, in addition to an overall site assessment to look for risks related stormwater runoff and other characteristics associated with the site’s location within the overall landscape.  One of the primary responsibilities of your engineer or architect is to determine if such conditions exist prior to you committing funds for construction.  Therefore, it is important that you make sure the septic system is one of the first things your engineer or architect pays attention to, and is not just an afterthought based on previous designs in your neighborhood or other areas where they may have worked in the past.
    • Poor construction methods can also cause a rapid failure of a septic system, occurring shortly after occupancy.  Excavation of the leaching field or trench must be performed with care, particularly in the clayey soils of southern Guam.  The contractor must not compact the bottom of the excavation with the excavator bucket, or “smear” the sides, which can create a microscopic but nearly water-tight layer of compacted clay.  Some soils are so fragile that even the act of pouring in the stone aggregate (gravel) may compact the soil and create such water-tight layers, and require that the contractor first place a layer of sand to avoid such action.  In addition, contractors can damage an absorption system after it is constructed by driving over it.  Once a leaching field or trench is constructed, there should be no driving or parking on it in order to avoid this type of failure, especially in areas with slow-percolating soils such as Southern Guam.
    • Failure due to clogging usually happens over a longer period of time (often many years), and is more common in soils that have slower percolation rates (for example less than 1 inch per 30 minutes), or have a high clay content.  This type of failure is mostly caused by the occupants of the house and what they flush into the septic system, or how often and how well the system is maintained.
  • How can I prevent my septic system from failing?
    Failure due to clogging usually happens over a longer period of time (often many years), and is more common in soils that have slower percolation rates (for example less than 1 inch per 30 minutes), or have a high clay content.  This type of failure is mostly caused by the occupants of the house and what they flush into the septic system, or how often and how well the system is maintained. Failure due to clogging is usually preventable through proper care and maintenance of the septic system.  Specific recommendations include:
    • Have your septic tank inspected and pumped to remove the accumulated solids at least every 3 years; more often for soil types that are at greater risk of this type of failure. This prevents the solids that naturally accumulate in the septic tank from flowing into the leaching field and contributing to clogging.  Remember: septic system pumping must be performed by a GEPA-registered contractor.
    • Avoid the disposal of food and cooking wastes into your septic system, especially fats, oils and grease. Make sure everyone in your household follows this rule. Do not wash food scraps into the sink, even if you have a garbage disposal.  Use strainers in the sink basin drains, instead.  Scrape excess food into the trash before washing dishes. Collect used cooking oil in jars or other containers, and never pour down the sink.  Soak up the grease from bacon and meat in paper towels and throw it in the trash, before completing your wash by rinsing it out in the sink.
    • Use only toilet paper that is certified to be septic-system safe. Don’t flush paper towels, disinfecting wipes, and other products that are not designed to dissolve.  Be particularly careful when purchasing toilet paper and cleaning products from foreign countries: many have been found in recent studies to not dissolve, which can contribute to early cogging of septic systems.
    • Don’t overuse cleaning products or dump chemicals down your drain. Ordinary use of household cleaning products is not a hazard. However, if you use too much, or dump excess paint thinner or other DIY or hobby-related chemicals into your system, you can kill the helpful bacteria that live in your septic system.  Damage to the natural bacterial activity of your septic tank can cause it to fill with solids faster and lead to premature clogging, as well running the risk of contaminating Guam’s aquifer.
  • Are septic system additives required to help keep my system operating properly?
    • You may have heard about products which claim to “rejuvenate” your septic system, or to eliminate the need to pump your septic tank. Though there is no evidence that most of these products cause any harm, there is also little evidence that they provide any benefit. Ordinary household sewage provides all the natural bacteria a septic system needs to operate, without any need for additives.
  • Variances: I can’t meet some requirements, can the GEPA Administrator approve a variance?
  • Permit Denials – Opportunity to Request a Hearing
    • The applicable laws and regulations do not provide for variances to the setback requirements, soil percolation requirements, lot size requirements, or other septic system design requirements.  The Individual Wastewater Disposal System Regulations at 22 GAR §12105(k) provides for the ability for anyone who is denied a permit to request a hearing before the Guam EPA Board of Directors, which shall affirm, modify, or revoke the denial, or issue the permit on the basis of evidence presented at the hearing.  Such request must be filed in writing within 15 days of the official notification of denial by Guam EPA.
  • Variances: Can GEPA provide a letter to my lender stating that the existing septic system at the property I want to buy (or sell) is adequate, if it does not meet setbacks?
    • GEPA does not get involved in real estate transactions, but can accommodate some requests for inspection and determination of existing septic systems to be “adequate”, depending on the availability of Agency resources.
    • In many of the cases where GEPA has been asked to provide such statements, the specific request has been related to dwellings with known non-compliance with setback distances, and no prior GEPA permitting records.  If no GEPA permitting records exist for an existing wastewater disposal system, and it does not meet current GEPA requirements for setbacks to wells, waters, structures, property lines, or any other requirement contained in the relevant laws and regulations, it is by definition “inadequate” [See 22 GAR §25106] and GEPA has no authority to issue any written statement claiming it to be “adequate” even if the septic system continues to function and does not meet the criteria for “defective” under 22 GAR §25107.
    • The year in which a septic system was built also has no bearing on GEPA determinations of adequacy.  All septic systems on Guam were required to be brought into compliance with the current requirements under the Toilet Facilities and Sewage Disposal Act during the mid-1980s, per 10 GCA §48104(c).  However, as stated under the section defining what constitutes an “adequate” existing sewage disposal system, the existence of records showing that the septic tank and leaching field was permitted, inspected and approved by GEPA or its predecessor at the time is sufficient for a determination of adequacy.
  • If sewer is installed in my neighborhood, do I have to connect even if my septic system is working fine?
    • The short answer is yes, but there are some exceptions for which the Administrator of GEPA may grant a variance.
     
    • The first thing to determine is whether public sewer is “available” to your home per its official meaning in Guam’s laws and regulations.  You are only required to connect to public sewer if it is considered to be “available” as described above under the section titled “How do I determine if public sewer is available?”.
     
    • The next thing to determine is if you will be able to connect to public sewer by gravity, with a minimum pipe slope of 1/8th of an inch per foot.  This may require an engineer to help you determine, but when new sewer is installed it is usually designed to ensure that all adjacent residents can be connected by gravity at the minimum pipe slope or greater.  Situations where gravity connection cannot be made are rare, but do happen – things to look for would be if your home appears to be below the grade of the adjacent roadway where the sewer was installed.  If you are able to determine that you cannot connect to the new sewer by gravity, you may qualify for a variance as described below, as long as your existing septic system is working and meets all setback requirements.
     
    • If public sewer is available, and you don’t qualify for a variance, you must connect within the timeframes provided in the Guam Toilet Facilities and Sewer Disposal Act (10 GCA Chapter 48) and the Connection to Public Sewer Regulations (22 GAR Chapter 25), which in general is five (5) years from the time public sewer first becomes available for existing dwellings served by adequate septic systems, but this may be reduced to 6 months or even less in some situations.  See the section below titled “How long do I have to connect to sewer if it is installed in my neighborhood?” for additional details and criteria required for time extensions.
  • About Variances
    • There are some situations in which connection to public sewer may not be possible or practical.  The Connection to Public Sewer Regulations at 22 GAR §25108 allows for variances in specific situations as follows.  In each case, a written request for the variance must be submitted to the Administrator for review, following the application requirements stated in 22 GAR §25108(d).  Variance decisions by the Administrator may be appealed, in writing, to the GEPA Board of Directors, following the procedures described in 22 GAR §25108(e).
      • New single family dwellings or duplexes [22 GAR §25108(a)(1)]: A variance to the connection requirement for a new dwelling or duplex may only be considered if “no other practical alternatives exist”.  Practical alternatives include relocating the proposed dwelling on the lot, or raising the foundation or plumbing so as to enable connecting to the public sewer by gravity.  Only new single family dwellings or duplexes are eligible for this variance.
      • Existing single family dwellings or duplexes with an “adequate” septic system [22 GAR §25108(a)(2)]: An existing dwelling which cannot be connected to public sewer by gravity (with a minimum grade of 1/8th inch per foot) may be granted a variance, but only if the dwelling is served by an “adequate” existing septic system.  An adequate septic system is defined in the regulations as one which has not failed, and meets all of the requirements of the regulations including setback distances from property lines and buildings. If the existing septic system is not adequate, the Administrator may still grant a variance but only if the lot is suitable for the construction of a septic system meeting all of the requirements of the regulations, and the owner agrees to construct and complete such system within thirty (30) days.
      • Existing single family dwellings or duplexes with an “inadequate” septic system [22 GAR §25108(b)]: In special cases a variance may be granted to allow the continued use of inadequate existing sewage disposal facilities serving a single family residence for up to a maximum period of five (5) years after sewer becomes available. Such variance shall be considered only when the disposal system is entirely adequate except for location, such as being less than ten (10) feet from the building or five (5) feet from the property line, and the Administrator finds the request will not endanger public health or pollute waters of the territory. Situations where a septic system does not meet setbacks to wells or Waters of the Territory are not likely to qualify for this variance.  If the dwelling cannot connect to the public sewer by gravity, with a minimum grade of 1/8" per foot, the variance may be extended.
      • Existing buildings with defective septic systems. No variances to the sewer connection requirement are allowed for buildings of any type which are found to be connected to a defective septic system.  A defective septic system is defined under 22 GAR §25107 and includes the following situations:
        • The septic system does not accept sewage and the sewage backs up into the attached building;
        • Sewage can be observed discharging to the ground surface from the septic system at any location;
        • Pollution of any Waters of the Territory can be shown, by dye studies or laboratory analysis, to originate from the septic system;
        • The existing facility is a cesspool, or the septic tank is not water tight
        • The septic tank shows evidence of structural failure
    • In all such situations, an existing building connected to a defective system must be connected to sewer.
  • How long do I have to connect to sewer if it is installed in my neighborhood?
    • If public sewer is available, and you don’t qualify for a variance, you must connect within the timeframes provided in the Guam Toilet Facilities and Sewer Disposal Act (10 GCA Chapter 48) and the Connection to Public Sewer Regulations (22 GAR Chapter 25), which in general is five (5) years from the time public sewer first becomes available for existing dwellings and duplexes served by adequate septic systems, but this may be reduced to 6 months or even less in some situations, as briefly summarized below:
     
      • Existing homes served by an adequate septic system: 5 years. However, no repairs, replacements, or additions to such facilities may be permitted, unless the home is first connected to public sewer.
      • Existing homes served by an inadequate or defective septic system: 30 days. This may be extended to 6 months provided GEPA finds that the defect or inadeauacy is not hazardous to health.
      • Existing homes served by adequate septic systems within the Groundwater Protection Zone (GPZ) where the density of septic systems exceeds four (4) septic systems per acre: 6 months (at the discretion of the Administrator)
  • What happens to my septic system after I connect to sewer?
    • The Connection to Public Sewer Regulations (22 GAR §25111) requires that the septic system be properly abandoned.  This will be a part of your permit requirements for connection to public sewer.  Proper abandonment requires having the contents of your septic tank pumped out by a plumbing contractor and filled completely with earth, sand, gravel or other similar material as approved by GEPA.

Additional Resources & Information

General Septic System Information

The US Environmental Protection Agency has excellent septic system resources.

The USEPA’s Frequently Asked Questions is a good start: https://www.epa.gov/septic/frequent-questions-septic-systems

Design Guidance

The USEPA design manuals offer a more in-depth look, and do not replace GEPA’s regulations, but can be used to supplement and provide excellent advice for designers on issues such as construction precautions, the most effective geometry for septic tanks, and other information:

1980 manual: 

https://www.epa.gov/sites/default/files/2015-06/documents/septic_1980_osdm_all.pdf

2002 manual update: 

https://cfpub.epa.gov/si/si_public_record_Report.cfm?Lab=NRMRL&dirEntryID=55133

Soils Information

The USDA’s Natural Resources Conservation Service maintains the official soil survey maps for Guam.  The soil survey can provide a good first look at the soil conditions that might be on any particular lot, but site-specific investigation is still required because soils typically vary even within small distances. 

NRCS Web Soil Survey main page (includes links to guides on how to use the information on the soils survey): 

https://www.nrcs.usda.gov/resources/data-and-reports/web-soil-survey

The University of Guam hosts a pdf copy of the original print edition, which may not be the most up-to-date in terms of latest revisions to the map, but some users may find it easier to use than the online soil survey:

https://www.uog.edu/_resources/files/wptrc/guam.pdf

Percolation Testing

Wetlands

The official wetland map for Guam is the US Fish and Wildlife Service National Wetland Inventory Map, per Executive Order 90-13, included as Appendix B of the Guam Water Quality Standards 22 GAR Chapter 5.  The USFWS NWI online mapping tool can be accessed here: 

https://fwsprimary.wim.usgs.gov/wetlands/apps/wetlands-mapper/

On-site wetland determinations performed by a GEPA professional are still required if work will be performed near a wetland, but this site provides useful information for planning because of the 300 foot setback required between a septic system and a wetland.

Waters of the Territory

Flood Zones

You can view the latest Flood Hazard Areas designated for Guam on the Federal Emergency Management Agency’s (FEMA’s) Flood Rate Insurance Map (FIRM) viewer here:  https://msc.fema.gov/nfhl

Northern Guam Lens Aquifer

The official aquifer map, for the purpose of interpreting GEPA laws and regulations, is the 1997 Department of Land Management Groundwater Protection Zone (GPZ) Overlay.  A scanned copy of the official map can be downloaded here:

Add link to GPZ Map

You can also view the GPZ in GEPA’s interactive map service, which allows you to see the GPZ boundaries in relation to other features to help pinpoint the location you are looking for.  The GEPA Interactive Map also allows you to view flood plains, wetlands, and other Waters of the Territory:

Under Construction

The University of Guam, Water and Environment Research Institute (WERI) also maintains a detailed map of the Northern Guam Lens Aquifer, which is the best reference available for determining groundwater flow direction, aquifer thickness, and a host of additional hydrologic data.  However please note that the GPZ map is the “official” map of the aquifer, to be used when determining compliance with requirements of GEPA laws and regulations related to the “aquifer”.

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