Chapter 5
Septic System Maintenance
from The Septic System Owner's Manual

In the last chapter we talked about what goes down the drain. Here we’re going to cover long-term periodic maintenance, which consists mainly of septic tank inspection and pumping when necessary. We’ll also discuss drainfield inspection.

People often say, “Oh, I’ve never had to pump my tank,” as if that were proof that their septic system works fine. But be aware, failure to pump tanks is (next to improper siting and design) perhaps the greatest single cause of septic system failure. Here’s what can happen:

Healthy tank Clogged tank

A. Scum at top: cooking fats, oils, grease, soap scum, other floatables B. Liquids in middle C. Sludge at bottom: solids heavier than water and what is left over after solids have been partially eaten by bacteria. Once sludge gets up to outlet pipe, it enters and clogs drainfield.

Drainfield Failure

After several years of use, a build-up of bottom sludge and floating scum will reduce the effective capacity of the tank, as shown in the “clogged tank” illustration on page 48. This means waste passes through the tank too fast, and solids eventually plug the pipes in the drainfield. The microorganisms in the drainfield no longer have an aerobic (with air) environment in which to perform their cleansing action; they are now struggling to survive in an anaerobic (without air) environment. Either untreated effluent begins surfacing on the ground or sewage backs up into house drains. At this point, the system has failed, and a new drainfield is required — expensive!

Inspection and Pumping

Inspect the Tank

How can you avoid drainfield failure? Inspect the tank at regular intervals and pump when necessary. In many parts of the country, it is recommended that tanks be pumped every three to five years, but recent studies indicate that a functioning tank, without abuse, may only need pumping every 10 to 12 years. Since there are many variables, we recommend an inspection every three to five years and basing pump-outs on inspections. As the years pass, you should be able to see the pattern of sludge and scum accumulation.

Keep a Record

Use a file folder (or get your wastewater district to get the Homeowner’s Septic System Guide shown on page 180) to keep a record of inspections and dates when the tank has been pumped.)

What Is Pumping?

Septic tanks are pumped by a licensed pumper with a vacuum tank truck. The pumper will use a 4-to-6-inch-diameter hose and vacuum everything out of the tank (both solids and liquids).

Waste pumped from a septic tank is called septage. It is approximately 5% solids and 95% water. (Raw sewage is 1% solids and 99% water.) The septage waste must be taken to a licensed disposal site because of the potential health problems with contamination. In many rural areas, private companies have developed septage disposal sites — generally evaporation ponds. In other communities, there may be a centrally located sewage plant that can handle the septage waste.

Where Is It?

Locating the Tank

You can save some money by locating the tank yourself and digging up the manhole covers. If the tank has no risers over inspection holes, and no diagram is available showing the location, you will have to probe for the tank, as follows: Use a long metal rod (1/2-inch rebar, bent over 90° to make a handle at the top) and begin probing where the main drain pipe leaves the house. Push the rod firmly down into the soil until you “feel” the drain pipe. Use a firm and steady push. Don’t punch or pound the rod as you can damage the pipe, particularly the pipe/septic tank connection. If the soil is too hard and dry for probing, try soaking the area with a garden hose.

Another method: There may be lush growth over the drainfield. Then the tank will be in an obvious place between the house drain and the drainfield. Or, you can run a snake down the clean-out to the tank and locate it with a metal detector.

		When you find the drain pipe at one spot, move a little further from the house and probe again. Continue along the path of the drain pipe until you locate the tank. The tank will probably be 1 to 3 feet underground and at least 5 feet from the building. Once you locate it, dig up both manhole covers. Or, if you’re lucky, the tank will have risers with sealed caps instead of the very heavy manhole covers of earlier models. If you plan to inspect your own system and don’t have these risers (see p. 6), we recommend that you have them installed. In addition to providing easy access for inspection, they keep out dirt and rainwater. In the meantime, use a rope through the metal handles on the concrete manhole covers to swing them up and off the tank. The tank is now ready for inspection and/or pumping. Note: Once you locate your tank, make a diagram of where it is for future reference, indicating number of feet from a particular point of the house.
Detail for retrofitting a riser on an existing tank
Know Where Thy Tank Lieth! B & M Contractors, of Bolinas, Calif., tells the story of some people who added a kids’ bedroom to their house without checking the location of the septic tank. All went well until one day, the system failed and it was then discovered that the room had been built over the the tank. To get to it, the pumpers had to pull back the rug, cut a hole in the floor, run their suction hose into the room through a window, and pump out the tank. Yuck! Tank Inspection Checking It Out You can save money by doing your own inspections. This way you will only call the pumper when needed. Inspection is done from above, by looking in through the manholes. Look around inside with a flashlight and perhaps even a hand mirror attached to a long pole. When checking tanks be sure to wear gloves and to wash your hands thoroughly with an anti-bacterial soap afterwards. However, if you’ve had no experience, it’s hard to know what to look for. If you intend to make your own inspections, we suggest you have the pumper come out the first time and that you watch how s/he performs the inspection. Ask questions. Then, the next time you should be able to do it yourself. WARNING: BE VERY CAREFUL AROUND SEPTIC TANKS. THE FUMES CAN KNOCK YOU OUT. FALLING INTO A SEPTIC TANK CAN BE FATAL. NEVER ENTER A TANK. FOR A SUMMARY OF SEPTIC SAFETY, SEE www.inspect-NY.com/septic/septicsafety.htm What to Look For Once the tank is open, here’s what to look for (assuming the tank has two compartments): Inlet Chamber A COOL SLUDGE/SCUM TOOL GET A 1-INCH CLEAR PLASTIC TUBE, 5 TO 6 FEET LONG. SLOWLY PUSH THE TUBE TO THE BOTTOM OF THE TANK, THEN COVER THE TOP WITH YOUR THUMB AND REMOVE CAREFULLY. WIPE THE TUBE OFF, AND YOU SOULD BE ABLE TO SEE A PROFILE OF YOUR TANK, INCLUDING SLUDGE, CLEAR EFFLUENT, AND SCUM. Homemade scum measuring device Homemade sludge-measuring device You can use hoe to measure depth to sludge, then a rod to measure depth of sludge. Odor: Odors should not be too obnoxious when you open the inlet side. (Odors will be a lot stronger when you stir the contents.) Insects: There should not be too many flies or flying insects present. Scum: Should be firm, with a crust, but not solid. It should be like pudding, a medium brown color, and 3 to 4 inches deep. By poking a stick through the scum, you can estimate the average thickness. Or, you can fashion an “L-rod,” as shown at the top right. You can figure on there being equal amounts of scum above and below the water line. ) Tip: Sometimes you can use a hose with high pressure to squirt a hole in the scum big enough to estimate its thickness. Sludge: You can use a long stick, but best is a concrete hoe (the type with two holes is best) and an extension handle wired or taped on. As you lower the hoe, it’s a little tricky is to tell when you first hit the sludge. Thus, proceed slowly. If you feel resistance halfway to the bottom, it needs pumping. Inlet tee: Concrete tees deteriorate. Be sure to check this. Outlet Chamber Scum: In a two-compartment tank, there should be little, if any, scum on the effluent side — the effluent should appear relatively clear. If there is much scum here (more than 2 inches), the tank needs pumping. If either scum or sludge is floating out the outlet, the tank needs pumping. In a one-compartment tank, a rule of thumb is that the tank should be pumped when the sludge is 20 inches and the scum is 10 inches. Outlet tee: If the inside of this tee is clogged, the tank is flooding, and this could indicate trouble with the drainfield. If the top is dry, it’s a good sign, since a wet top would indicate the tank is flooding. If the tank is flooding, there is no air at the top of the tank, and this anaerobic condition can result in tank deterioration. Outlet tee deterioration: A concrete or ceramic outlet tee in a tank can deteriorate above the water line due to sulfuric acid. This is easy to replace with a plastic tee and should be inspected periodically. Baffle wall deterioration: The baffle wall between the two chambers can deteriorate as well. Consider putting an effluent screen in place rather than trying to repair the baffle wall, or replace the tank. A local septic tank inspector mentioned an owner who went into his tank to repair a baffle wall and was sick for over a year as a result. In Oregon, for example, most new tanks are now one chamber with an effluent screen. Cost for installing a screen might be $200 to $300. (See pp. 8–9.) Insects Mosquitoes and flies can be a problem if they enter and breed in a septic tank. Strangely, this is not often mentioned in literature on the subject. Mosquitoes and flies can enter through the plumbing vent of the house, go down through the 4-inch drain pipe and through the inlet tee to the tank. They can then breed in the tank and travel via the same route, reversed, to the outside world. You can cover the top of the vent with a capper of stainless steel screen. Another place for mosquito entry can be tanks with wood or fiberglass risers; here the manhole covers can be sealed with roof patch or a plastic sheet over the lids, then covered with a few shovelfuls of sand. If the Tank Needs Pumping Try to be there when the pumping is done. Lean over the shoulder of the pumper and make sure the tank is pumped completely. We heard about one company that pumped only the liquids and no solids. As the tank is pumped, it should be cleaned out as thoroughly as possible with a hose. There will be plenty of bacteria left to reactivate the system even when the tank is thoroughly cleaned. It is difficult to suck out the bottom 2 to 3 inches of sludge, particularly if it contains a lot of sand. The pumper should hose down the sludge on the bottom when it is exposed so that it will partially liquefy and can then be sucked out. A high-pressure squirter, not a thumb applied to the hose, should be used. Drainfield Inspection If the drainfield was properly designed and installed (and the tank functions properly), it should be mostly maintenance-free. However, here are some tips. Drainfield Test Lush plant growth over the drainfields (or tank) may be a sign of sewage surfacing. Here’s one way to check the drainfield’s absorption capacity: run 40 to 80 gallons of water into the tank and, with the outlet riser open, watch how long it takes to drain into the drainfield. A slight back-up from the normal tank water level (the bottom of outlet pipe) is OK. The water level may rise H to 1 inch, but if the field is unclogged (and not flooded), a fully-flooded tank should drop to normal in five to ten minutes. The “French Drain” If the original installation didn’t allow for good drainage of surface waters (rain or run-off) around the drainfield, drainage ditches (with proper setbacks from the drainfield) may be needed. Also, a high water table in winter and/or dense soil can cause effluent to surface, causing bad odors and a possible health hazard. Roots Trees or shrubs with aggressive, water-seeking roots growing near the drainfield can cause real problems in conventional drainfields. The roots will seek out water, and can run inside the drainfield pipes and choke off the flow of effluent. Willow roots are notorious drainfield invaders. Dual Drainfields If you have a dual drainfield with a diverter valve, rotate the valve to the alternate field every six months or year. (See p. 20.) This allows the trenches to dry out and rejuvenate. Soil Compaction Be sure no one parks cars over the drainfield. It will compact the soil and reduce the aerobic capacity of the drainfield. Also, be sure cars don’t drive over the inlet and outlet pipes to the septic tank. This can snap the pipes and even cause the tank itself to crack. Pump Maintenance For mounds, sand filters, STEP systems, and lift systems for gravity drainage fields: Run the pump through its cycle periodically to make sure there are no leaking pipes. Pumps should have alarms. Pumps should have check valves. Note: in areas of severely cold weather, check valves can be detrimental to proper pump operation. Keep Those Hands Clean! Just as you can pick up a cold or the flu by getting germs on your hands and then touching your hands to your nose, you can pick up some much nastier organisms if you have manual contact with an open tank or drainfield. If you’re going to do your own inspection or repairs, wear gloves and wash your hands scrupulously afterwards. Never Been Pumped The fallacy: You often hear a homeowner say, “Oh, I’ve never had to pump my tank.” The irony: Typically, the homeowner has never had any septic system problems and thinks this means nothing need be done. The remedy: Just as you need to check the oil level in your car so it doesn’t get too low, you need to periodically check the solids level in your tank so it doesn’t get too high. POLITICAL PUMPING ONE HOMEOWNER IN OLYMPIA, WASHINGTON HAS A SIMPLE REMINDER TO PUMP HIS TANK. HE PUMPS IT OUT EVERY YEAR THERE IS A PRESIDENTIAL ELECTION Summary Sludge and scum accumulate in every septic tank. How much and how fast depend upon a number of conditions. You can save money by locating the tank yourself and inspecting scum and sludge levels to determine when pumping is necessary. (However, there is a learning curve.) Inspect your tank every three to five years until you determine the inspection frequency required for the future. Scum and sludge must be pumped on a regular basis or system failure can result. Drainfield operation can be maximized by checking the tank’s outlet tee, by testing the drainfield’s absorptive capacity (see pp. 52–53), by ensuring good drainage, and by avoiding soil compaction. OUT OF SIGHT, BUT IN YOUR MIND! copyright © 2007 - Shelter Publications, Inc

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