To extend the life of the septic system and prevent waste water backups, here are some
recommendations:
Basics: The most basic factor is the extent of use - the more waste water that is
produced, and the more waste that is in the water, the more often the septic tank
must be pumped and the shorter the life of the entire system will be.
General: Any inorganic material (metals, plastics, etc.) that goes down drains will not
properly break down in the septic tank and will need to be removed by pumping - avoid
allowing these materials to go down drains. Normal amounts of typical household cleaners
will usually not harm septic systems, but excessive amounts of particularly harsh cleaners
(strongly anti-bacterial, chlorine bleach, drain cleaners, etc.) may interfere with
the microbial breakdown processes normally present in the septic tank.
By reducing/stopping use of these products, the normal microbial breakdown process will
usually recover without any special assistance. Other chemicals may damage the waste water
system, and allowing them to go down drains should be avoided.
Toilet drains: Only two solids should ever be flushed down toilets - what comes out of you
and toilet paper. Most other items typically flushed down toilets will not break down
properly in the septic tank and will reduce the reliability of the septic system and result
in more frequent septic tank pumping. As a general rule, any product that is advertised
as "strong and absorbent" (e.g. paper towels, feminine hygiene products, diapers) should
be considered "clog creating and backup producing" from the perspective of the septic
system. Toilet paper that is "extra soft" or "strong" will also typically not break down
as quickly in the septic tank. Toilet paper that contains recycled content is generally
better for septic tanks. Look for toilet paper that is labeled as "septic safe".
Kitchen sink drains: Waste disposers that grind up solid wastes can be used with septic
systems, but this increases the amount of solids discharged into the septic tank and will
increase the frequency at which the tank should be pumped out. As a rule, prevent any
organic materials that you would not normally eat from going down sink drains (e.g. egg
shells, bones, some fruit skins or cores, stems, outer onion skins, etc.) as these will not
break down in the septic tank. Consider composting organic wastes instead of sending them
down drains - this will both extend the useful life of the septic system and improve soils.
Avoid allowing fat or grease to go down drains. Fat and grease will not only clog drains,
but can form a barrier in the scum layer of the septic tank that prevents the absorption of
oxygen into the tank water, interfering with the normally present bacterial action in the
tank.
Tub, shower and lavatory sink drains: The most significant concern with these drains
is hair. In addition to causing clogs, hair also will not break down in the septic system.
Avoid allowing excessive amounts of hair down drains. Normal use of typical personal care
products will not harm the septic system.
Washing machine and dish washer drains: Normal amounts of typical detergents and related
products are not a problem.
Septic tank pumping: Septic tanks need to be pumped out periodically. The frequency of
pumping is dependent on the size of the septic tank and the amount of use the septic
system gets. The table below lists the recommended pumping interval (in years) as a function
of septic tank size and number of people regularly using the septic system. Note that if
the system has increased loading conditions from what is typical (e.g. regular use of a
kitchen sink disposer, doing laundry for others not living in the home, etc.), tanks
should be pumped more frequently than the interval listed here.
| Septic Tank Pumping Frequency (years) |
Septic Tank
Size (gal) |
Household size - Number of Occupants |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
| 500 |
5.8 |
2.6 |
1.5 |
1.0 |
0.7 |
0.4 |
0.3 |
0.2 |
0.1 |
--- |
| 750 |
9.1 |
4.2 |
2.6 |
1.8 |
1.3 |
1.0 |
0.7 |
0.6 |
0.4 |
0.3 |
| 900 |
11.0 |
5.2 |
3.3 |
2.3 |
1.7 |
1.3 |
1.0 |
0.8 |
0.7 |
0.5 |
| 1000 |
12.4 |
5.9 |
3.7 |
2.6 |
2.0 |
1.5 |
1.2 |
1.0 |
0.8 |
0.7 |
| 1250 |
15.6 |
7.5 |
4.8 |
3.4 |
2.6 |
2.0 |
1.7 |
1.4 |
1.2 |
1.0 |
| 1500 |
18.9 |
9.1 |
5.9 |
4.2 |
3.3 |
2.6 |
2.1 |
1.8 |
1.5 |
1.3 |
| 1750 |
22.1 |
10.7 |
6.9 |
5.0 |
3.9 |
3.1 |
2.6 |
2.2 |
1.9 |
1.6 |
| 2000 |
25.4 |
12.4 |
8.0 |
5.9 |
4.5 |
3.7 |
3.1 |
2.6 |
2.2 |
2.0 |
| 2250 |
28.6 |
14.0 |
9.1 |
6.7 |
5.2 |
4.2 |
3.5 |
3.0 |
2.6 |
2.3 |
| 2500 |
30.9 |
15.6 |
10.2 |
7.5 |
5.9 |
4.8 |
4.0 |
3.5 |
3.0 |
2.6 |
Use of special septic system additives: It is the general consensus of industry professionals
(who are not trying to sell you something) that special septic additives are not required.
Typical septic systems achieve acceptable performance simply by allowing natural processes
to occur that require no special assistance or additives.
For more details about septic systems, see the
Inspectapedia website.
