Tips for Maintaining Your Septic System – New Hampshire & Maine

Tips for Maintaining Your Septic System – New Hampshire & Maine


  • Do not put too much water into the septic system; typical water use is about 50 gallons per day for each person in the family.
  • Do not add materials (chemicals, sanitary napkins, applicators, and so on) other than domestic wastewater.
  • Restrict the use of your garbage disposal.
  • Do not pour grease or cooking oils down the sink drain.
  • Make a diagram showing the location of your tank, drainfield, and repair area.
  • Install a watertight riser over the septic tank to simplify access.
  • Have the effluent filter in the septic tank cleaned periodically by a professional.
  • Have the solids pumped out of the septic tank periodically.
  • Maintain adequate vegetative cover over the drainfield.
  • Keep surface waters away from the tank and drainfield.
  • Keep automobiles and heavy equipment off the system.

Do not plan any building additions, pools, driveways, or other construction work near the septic system or the repair area.

Will I Need to Pump the Tank?

Yes. After a few years, the solids that accumulate in the septic tank should be pumped out and disposed of at an approved location. If not removed, these solids will eventually overflow, accumulate in the drainfield, and clog the pores (openings) in the soil.

This blockage severely damages the drainfield. Although some clogging of soil pores slowly occurs even in a properly functioning system (the biomat described earlier), excess solids from a poorly maintained tank can completely close all soil pores so that no wastewater can flow into the soil. The sewage effluent will then either back up into the house or flow across the ground surface over the drainfield.

If this happens, you may need to construct a new drainfield on a different part of your lot. Pumping the septic tank after the soil drainfield has become completely clogged will not rejuvenate the system. It will provide only a few days of reprieve until the tank fills up again. Once the soil has become completely clogged, it is usually necessary to install a new drainfield or an advanced pretreatment unit, or both. This can have a significant negative effect on your landscaping and yard, as well as being expensive. An ounce of prevention is worth a pound of cure with septic systems.

How Will I Know When to Pump the Tank?

The frequency with which you will need to pump depends on three variables: the tank size, the amount of water used by your family, and the solids content of your wastewater. If you are unsure about when to have the tank pumped, have a professional operator observe the rate of solids accumulation in the tank each year. He or she can clean and replace the effluent filter cartridge in the tank at the same time.

The tank should be pumped if the sludge layer at the bottom of the septic tank has built up to within 25 to 33 percent of the tank’s liquid capacity or if the scum layer in the tank is more than 4 to 6 inches thick. Therefore, a typical 1,000-gallon tank with a 4-foot liquid capacity should be pumped when the solids reach 1-foot thick in the tank bottom.

If the tank is not easily accessible and the rate of solids accumulation cannot be checked yearly, then you may wish to inspect and pump it according to the frequency guidelines in Table 1. Your local health department should be able to tell you the size of your tank. When inspecting the tank, check the effluent filter (or for older systems check the sanitary tee or the outlet baffle to be sure that it has not broken off and dropped into the tank).

Also, be sure to have both compartments of the tank pumped (note the two compartments shown earlier in Figure 2).

If the septic system is not used very often (as in an infrequently used vacation home with a correctly sized tank), it will probably not need to be pumped as frequently as indicated in Table 1. If you use a garbage disposal, the tank may need to be pumped more frequently. After a few inspections, you should be able to adjust the schedule according to the rate at which solids accumulate.

Table 1. Estimated septic tank inspection and pumping frequency (in years).
Tank Size (gallons) Number of People Using the System
1 2 4 6 8
900 11 5 2 1 <1
1,000 12 6 3 2 1
1,250 16 8 3 2 1
1,500 19 9 4 3 2
Source: Adapted from “Estimated Septic Tank Pumping Frequency,” by Karen Manci, 1984, Journal of Environmental Engineering. Vol. 110(1):283-285.

What Should Not Be Put into the Septic System?

Make sure you are aware of the types and amounts of extra waste materials that are poured down the drain. Limiting the use of your garbage disposal will minimize the flow of excess solids to your tank. Garbage disposals usually double the amount of solids added to the tank.

Do not pour cooking greases, oils, and fats down the drain. Grease hardens in the septic tank and accumulates until it clogs the inlet or outlet. Grease poured down the drain with hot water may flow through the septic tank, but then it can clog soil pores completely and ruin the drainfield.

Pesticides, paints, paint thinners, solvents, disinfectants, poisons, and other household chemicals should not be dumped down the drain into a septic system because they may kill beneficial bacteria in the septic tank and soil microorganisms that help purify the sewage. Also, some organic chemicals will flow untreated through the septic tank and the soil, thus contaminating the underlying groundwater.

If your home has a water treatment system, such as a water softener, the discharge pipe from the backwash should not be connected to the waste plumbing system or septic tank.