Colorado only - Infiltrator IM-540, CM-1060 & IM-1530 septic tanks

Infiltrator's IM Series injection molded (and CM compression molded) polypropylene construction septic tanks feature heavily-ribbed bodies capable of dry burial up to four feet deep, structurally reinforced manways, fiberglass bulkheads, and advanced mid-seam gasketed connections making them far superior to rotationally molded plastic. Note there is no strength difference between compression and injection molding, it is simply a different technique whereas rotationally molded septic tanks are far weaker, inferior one-piece construction that often requires being filled with water before backfilling. Infiltrator heavy-duty septic tanks are rated for dry burial up to 4 feet deep. IM-540 single compartment has a 552 gallon working capacity at 5 foot 5 inch (65") long, 5 foot 2 inch (62") wide, 4 foot 7 inch (55") tall, and 170 pounds. CM-1060 two compartment has a 1111 gallon working capacity at 11 foot 2 inch (134.2") long, 61.7 inch wide, 54.5 inch tall, and 331 pounds. IM-1530 two compartment has a 1537 gallon working capacity at 14 foot 8 inch (176") long, 5 foot 2 inch (62") wide, 4 foot 7 inch (55") tall, and 500 pounds. Lifting ropes are installed for ease of installation without a crane. We have not sold any other brand for well over twenty years because Infiltrator septic tanks are simply the best.

For over 30 years, we have been providing FREE consultation to all clients. Engineered plans are traditionally bare minimum acceptable standards, never mentioning any optional parts. Inspectors and engineers very rarely, if ever, discuss design choices that will improve performance and safety, increase longevity, expedite construction, and prepare for future repairs. Unlike other plumbing supply firms, we take an interest in your project, providing our clients with free consultation. We encourage you to mail a copy of your site plan for free review with purchase of an Infiltrator septic system. The Natural Home is not an engineering firm; we do not provide any engineering services. Please email service@thenaturalhome.com with any questions or concerns.

Delivery is FREE by company truck within about a 50 mile radius of central Denver. North to Fort Collins and Greeley, South to Franktown and Monument, East to Deer Trail and Tampa, West to Georgetown and Silver Plume, and SouthWest to Bailey and Conifer. Delivery a few miles outside of this radius may be possible for a fee. We can normally schedule an AM or PM delivery given at least three days advance notice, weather permitting. Designated receiver must be on site and waiting with machinery to unload septic tanks using installed lifting ropes. Or you can will-call pick up in person at our central Denver area warehouse with a pre-paid order. Warehouse will-call hours are 7:30 AM to 4 PM on Monday through Thursday and 7:30 AM to 2 PM on Friday. Payment at the yard is not possible to arrange. Infiltrator tanks are not shipped outside of Colorado. Outside of Colorado, contact the manufacturer at InfiltratorWater.com or info@infiltratorwater.com or 800-221-4436.

Infiltrator heavy-duty septic tanks & risers

$2067 ($1963.65*) IM-1530 1537 gallon capacity
2 compartment, 3 manhole 62" wide by 55" high by 176"
Kit includes 3 lids, 2 rubber grommets & 2 PL-68 drop tees

$1597 ($1517.15*) CM-1060 1111 gallon capacity
2 compartment, 2 manhole 61.7" wide by 54.5" by 134.2"
Kit includes 2 lids, 2 rubber grommets & 2 PL-68 drop tees

$1027 ($975.65*) IM-540 with 552 gallon capacity
1 compartment, 1 manhole 62" wide by 55" by 65" long
IM-540 tank kit includes 1 grommet & 1 PL-68 drop tee

EZ Snap stackable risers $80 ($76*) for 12" tall
$50 ($47.50*) for 6" tall and $35 ($33.25*) for 2"
At least one 12 inch riser per manway in Colorado climate
Infiltrator tanks are rated for dry burial up to four feet deep

$47 ($44.65*) Safety Star manway grids
Perhaps not required on permit, but sensible insurance

$107 ($101.65*) Septic tank filter kit
Every tank needs an outlet filter - No parts to ever replace
Comes with housing and handle, plus a free 5" hole saw

$49 ($46.55*) 7-hole Tuf-Tite distribution box
Free plugs & seals - specify SDR35 or Sch40 pipe
$22 ($20.90*) each for 6" tall D-box risers
May not be required, but smart to take lid to grade

$2 ($1.90*) each for D-box speed levelers
Even distribution and allows shut-off to select runs

$59 ($56.05*) 9-hole Tuf-Tite distribution box
Free plugs & seals - specify SDR35 or Sch40 pipe
$53 (*$50.35) each for 12 inch tall Tuf-Tite risers
$30 (*$28.50) each for 6 inch tall Tuf-Tite risers
$32 (*$30.40) each for green domed riser lids

$239 (*$227) 10-hole Rhino distribution box
24 inch diameter with Ten (10) potential openings
Four (4) Free 3001-SN seals fit 2", 3" or 4" pipe
Seals require 5-1/8" (130mm) hole saw to install
Here's a 5-1/8 inch hole saw on Amazon for $14
$7 (*$6.65) each for additional 3001-SN seals
$32 (*$30.40) each for 2 inch tall Rhino risers
$53 (*$50.35) each for 6 inch tall Rhino risers
$88 (*$83.60) each for 12 inch tall Rhino risers

$107 Flow director valve tee ships via UPS
Splits effluent 50/50 or 100% in one direction

$347 ($329.65*) Fluid Dynamics FDS216 siphon
non-electric 2" outlet 16" draw-down installed in IM-540

$727 ($690.65*) 300 gallon spherical pump tank
54" diameter by 51" tall with elevated pump stand on bottom
44" to inlet center and 42" to outlet center 8" square flat areas
$277 ($263.15*) 15" tall risers & $327 ($310.65*) 24" tall risers

Pipe and fittings are less expensive to purchase at HomeDepot or Lowes
Pumps, floats, alarms, and control panels are also cheaper to buy online
If you can't find any special parts, we can source them with system purchase

Orenco products are less expensive to purchase online from volume sellers
They are rarely specified in Colorado, so we don't stock any Orenco systems
With purchase of a septic tank, we can help source Orenco products for you

$209 for 4 foot by 250 foot heaviest-duty 5 ounce woven geofabric ships UPS
Fabric is draped over chamber top to prevent sand and silt from washing inside
Available in 3, 4, 5 and 6 foot widths and 30, 60, 90, 120 and 250 foot lengths

Geotextile fabric & liners for perforated pipe leach fields and mound systems
Fabric delivery is only available with purchase of an Infiltrator system. Not shipped separately.
Please note that all Infiltrator and geotextile fabric prices are subject to change without notice.
$157 for 6 foot by 300 foot (200 sq yd) of 2 ounce sq yd non-woven polypropylene
$257 for 10 foot by 300 foot (333 sq yd) of 2 ounce sq yd non-woven polypropylene
$307 for 12 foot by 300 foot (400 sq yd) of 2 ounce sq yd non-woven polypropylene
$769 for 12 foot 6 inch by 360 foot (500 sq yd) of 4.2 ounce sq yd non-woven 'Mirafi'
$929 for 15 foot wide by 360 foot (600 sq yd) of 4.2 ounce sq yd non-woven 'Mirafi'
$477 for 6.35 foot by 100 foot roll (635 sq ft) of 30 mil PVC mound liner membrane

Infiltrator septic tank system parts list options

* 1500 gallon Septic Tank is always recommended when a 1000 gallon tank is 'allowed' on your permit. Especially in a cold climate, the additional 50% volume translates into longer retention time for better settling of waste and much greater leach field protection against bio-mat formation. The investment pays off big in the long run by pumping the septic tank less often and ensuring leach field longevity. Plus, a 1500 gallon tank may allow for adding more bedrooms to your home in the future.

* Manhole Risers must be installed on all manways to allow lid removal at ground level without dirt falling into the tank. Two (2) manways on the IM-1060 and Three (3) on the IM-1530 tank with 2, 6, and 12 inch tall risers available. Tanks can be buried up to four feet deep, with burial at least 12 inch deep the norm. The lid is generally covered with geotextile fabric and a few inches of mulch, gravel, or pavers to protect it from sunlight damage. This product cannot be shipped later.

* Safety Star Grids may not be "required" by your engineer, but they are a most highly recommended common-sense safety feature. These 250 pound rated reinforced fiberglass safety grids screw into the manway risers with enough space left open in the center to insert a septic pumper hose and remove the filter for cleaning. This product cannot be shipped later.

* Septic Tank Filter should always be installed on the outlet side of all septic tanks. Rated for up to 800 gallons per day, our kit comes with a handle extension and PL-68 'Versa-Tee' housing which can adapt to a 4 inch SDR35 or Sch40 pipe. Kit includes a free hole saw kit for cutting 5 inch diameter holes for septic tank inlet and outlet. This product ships via UPS Ground.

* Geotextile Soil Fabric can be installed above chambers to prevent migration of surrounding soils and keep it from entering the chambers. Recommended in wet and potential flooding areas with sandy or silty soil. Our 4 foot wide rolls of best heaviest-duty woven 5 ounce geotextile fabric ship separately via free UPS Ground.

* D-Box Speed Levelers are insurance against distribution boxes ever being knocked out of level. They can be adjusted to evenly split flow to all outlet pipes. Speed levelers also allow you to shut flow off to individual runs seasonally, so they can dry out and recuperate. This product cannot be shipped later.

* D-Box 6 inch risers bring the distribution box lid up closer to the surface so you can adjust the speed levelers. Local regulations may require risers for ease of inspection and maintenance. The D-box lid is normally covered with geotextile fabric and a few inches of mulch, gravel, or pavers to protect it from sunlight damage. This product cannot be shipped later.

Over 30 years of do-it-yourself design tips and rules of thumb

All installation tips detailed here apply equally to any brand or type of septic tank. With 64 very independent counties in Colorado, each with their own unique set of regulations, and an infinite variety of site and soil conditions, we cannot predict what will be required. Always check with your building department to confirm local regulations prior to planning any septic or greywater system to confirm what is required for your property. The Natural Home is not an engineering firm; we do not provide any engineering services, soil testing or on-site installation work.

Always install at least one manway riser above every septic tank manhole. Without a riser, it is impossible to open lid for servicing without sending debris down into the tank's manhole. Conventional to install at least one 12 inch tall riser for each manway, but you can certainly bury deeper in a cold climate. Infiltrator tanks are rated for dry burial up to four feet deep. Risers are stack-able available in 2, 6, and 12 inch tall and snap together (no screws needed). Lid should be buried at least a few inches below grade, deeper burial in a cold climate. Even in the warmest climate, best practice is to cover lids with landscaping fabric and mulch or native soil to protect against UV damage. Manway safety grids should be installed on every manhole to prevent accidents. Fiberglass reinforced, manway safety grids screw into place within the riser for a solid installation with enough open room in the center of the grid to allow insertion of septic pumper hose and removal of the septic filter for cleaning. Infiltrator Safety Stars for installation in the 24 inch diameter EZsnap riser.

cold climate installation guidelines

In a cold climate, especially with minimal snow cover, it is critical to bed tanks in plenty of +/- 3/4 inch gravel. Round river rock is fine for bedding pipe and tanks. Avoid large 2+ inch rocks and sharp, crushed gravel. It is possible to set tanks atop a sand bed to make it easier to level, but sides and top must be gravel in a cold climate. By bedding in at least eight inches of gravel, cold water and frost cannot come in contact with the sides and bottom. Take the additional step of covering the top of the tank with a reinforced poly tarp (or pond liner) that extends at least five feet in every direction and mounding underneath to encourage water to drain away. For more insurance in the coldest climates, and when usage is minimal, add at least 2 inches of foamboard insulation underneath the tarp, on a flat substrate before mounding. Dry soil is warm soil. A few inches of foam board insulation glued and screwed to the bottom of lids is best practice in colder climates. Warmer septic tanks provide for faster, better waste treatment which protects leach field longevity.

bed all leach field pipe in plenty of gravel

All pipes must be well-bedded in at least six inches of +/- 3/4 inch gravel to avoid frost issues or soil settling and heaving pipe off-level. Best practice is first connection (joint) at effluent pipe coming out of foundation be made with rubber boot coupler. Common mistake is solvent welding that first joint with a hard fitting and not bedding pipe. Should the newly installed pipe run settle, a rubber boot coupler will adapt, unlike solvent welded joint. Pipe from foundation to septic tank slopes maximum of 1/4 inch per foot. Too steep of slope and water will bypass solid waste in the pipe, eventually clogging it. Slope minimum 1/8 inch per foot from septic tank to distribution box and leach field. Much steeper is possible, but best to level-off prior to the distribution box or the turbidity will affect equal splitting to runs. Use lots of purple primer on all pipe joints and splash it around to allow inspector to clearly see everything was properly primed before solvent welding.

Four inch diameter sewer pipe comes directly from cleanout, immediately adjacent foundation, to the septic tank. No bends should be installed between house and septic tank or toilet waste may settle in the line and eventually block flow. After the septic tank, sewer pipe can make bends as need be. Just maintain 1/8 to 1/4 inch per foot slope until the septic tank. Greater slope than 1/4 inch per foot may allow water to flow around toilet waste, allowing it to settle and block flow. Less than 1/8 inch drop per foot and you may leave flat sections or dips that can freeze. When designing site plan, you are not limited to coming in one end of tank and out the opposite end. Infiltrator tanks can be plumbed from three directions on both ends. 

Critical detail is to bed all pipe, fittings, and distribution boxes well in at least six inches of gravel to ensure level is maintained and frost is not an issue. Best practice is to 'wet-set' distribution box atop a bag or three of Quikrete to ensure level is maintained. Wet-set refers to pouring dry concrete mix under and around and then wetting it with water. You can pre-mix the concrete or set with minimal water in the field with 'fence post' dry mix. Fill the bottom of D-box with water up to hole openings to give it some weight. Water will exit all outlet holes evenly when box is perfectly level. Bringing lid up to near the surface with D-Box risers will allow use of Speed Levelers to dial-in accurate distribution. Rotating speed levelers upside down allows individual runs to go fallow and dry out seasonally to help protect longevity.

Concerning the use of Sch40, SDR35, or ASTM 3034 pipe in septic systems, SDR35 'sewer, drain, vent' pipe with 3034 fittings is adequate for wastewater systems outside the home foundation.  Sch40 thick wall pipe is only required for pressurized water systems. Sch40 might help should you ever drive over the system, but one should never ever drive over any pipe. At the very least, you may create a dip in the line and block flow. Should you be forced to drive over a section of pipe, always 'sleeve' the four inch pipe inside an outer six inch Sch40, or thicker, galvanized metal pipe.

Individual Sewage Disposal System ISDS rules vary

*   When you apply for building permit, the local health department official will most likely help you design the sewage disposal system and may even offer to have their office perform a soil test (LTAR) in lieu of a percolation test. This involves digging a soil profile hole which is generally an eight foot deep trench in the area of the leach field. Most building departments wisely require a visual confirmation that there are no problematic soil conditions, groundwater, or bedrock in the area where you intend to put the leach field. But check with your local officials, as you may only need to provide a site plan survey (ILC) of your property (to establish setbacks from buildings, wells, streams, and property lines) and fill out some forms. 
*   Your septic system site plan is typically drawn right on top of your property survey showing the septic tank and leach field 'setbacks' with tank 5-10 feet from the house, the leach field at least 20 feet from the house, at least 100 feet away from wells and streams, 25 feet away from dry gulches, and 10 feet away from the property lines. Or whatever the local regulatory officials require, so always check with the county first for minimum setbacks. Ensure easy access to septic tank for the pumper truck. Clear any obstacles while you have the backhoe on site and consult with pumping company about how close they need to get with their truck. If they have to drag hose very far it will cost you.
*   The home's sewer line drain pipe needs to slope 1/8 to 1/4 inch per foot downhill to the inlet side of the septic tank and the outlet pipe needs to flow downhill at least 1/8 inch per foot downhill to the leach field, where the septic tank effluent enters a manifold or distribution D box. Beyond the manifold or D box the leach field trenches (for an Infiltrator chamber system) are excavated perfectly level at a depth of at least seven inches below the grade of the manifold pipes or D box (for chambers). And covered with at least one foot of soil atop the trench or chamber. Trenches can be deeper, if the site dictates, but rarely more than three feet below finish grade.
*   If the leach field is uphill from the septic tank (or if the local health regulations simply require it) a lift station is installed in-line after the septic tank. An electric pump in the lift station tank forces effluent out to the leach field every time it fills to a certain level 'dosing'. Most ISDS codes allow field size reductions with dosing or automatic siphons, so there may be an advantage to installing a lift station when building on small lots and/or with nearby streams or ponds. We do not sell pumps since they are readily available locally and electricians tend to prefer supplying parts.
*   Never grind (macerate) your sewage before sending to septic tank unless absolutely necessary. Pumping treated sewage (after septic tank) up to the leach field with lift station is always an option, but do not macerate (pump) effluent prior to the septic tank. The septic tank operates by digesting solids and settling sludge to the bottom and allowing grease to float to the top of the septic tank. Macerating the sewage before entering the septic tank will create a septic tank without any large solids, just a cloud of ground up sewage particles. When you send these particles out to the leach field, you are bound to eventually clog the soil with bio-mat and then the leach field fails.
*   Never use bleach, drain cleaner, or harsh soaps with a septic system. Bleach and detergents kill the helpful bacteria that thrives in a healthy septic tank to optimally process toilet waste. Lack of proper septic tank bacteria will cause your leach field to fail from excessive bio-mat accumulation.
*   Winter freezing is rare with proper installation and constant usage. Always have your tank pumped in the spring, never in the fall, or low bacterial activity may fail to keep the sewage warm. Surface freezing inside a septic tank can be avoided by bedding tanks in at least one foot of gravel (crushed or river rock). Drainage of the area under and around tank and above the tank, with waterproof tarp diverting drainage at least three feet away. If you can keep the water away from the sides of the tank, you can retain more heat in the dry ground and help speed decomposition of waste. In practice, this amounts to backfilling up to top of tank, sloping the ground away (mound) around perimeter, and then laying down a plastic tarp. A good tip is to set down a layer of straw before the tarp - it will cushion against rock damage and provide insulation. In extreme climates, a layer of two or four inch thick extruded polystyrene (EPS) foamboard insulation can be installed below the tarp.
*   If allowed, always divert greywater to a separate leach field (see the greywater page for details). Greywater contains soaps, which are designed to kill bacteria (clean and disinfect things). You want to encourage helpful "good" bacteria (digesting anaerobic cultures) to grow in your septic tank, not kill them with soap laden graywater. If you cannot divert all of your greywater, just diverting the washing machine discharge will make a big difference in performance and eliminate a large portion of a home's effluent, taking the load off your leach field.

pumping tanks and a warning to immediately refill

never use ANY septic additives or enzyme digesters

Properly sized two compartment septic tanks operate just fine without potentially dangerous additives. Breaking down fats and solids in the septic tank with digestive enzymes simply allows these now much smaller particles to pass through the septic filter where they reunite in the leach field, forming a dense bio-mat. The FDA has never approved any additives; none are considered safe or effective. You don't want these additives finding their way into the groundwater where they can be used for irrigation and drinking. Leach field distance from the wellhead (100 to 200 feet) is no guarantee of safety, it's just an arbitrary number locally assigned to allow residential construction on smaller half acre lots. Lateral water (sewage effluent) movement underground is extremely unpredictable at certain times of the year and will easily contaminate your well. Any chemical (or enzyme) which digests sewage should frighten a reasonable person to allow in their drinking or irrigation water.

septic system effluent treatment area options