Sewage system information for recently rural residents.
by Cliff Turner
It's easy to get information on how to maintain a compost bin, but septic tanks, which operate with a similar biological breakdown of food or waste, seem more mysterious. The septic tank is an essential part of a sewage system. Here are some points to remember about the "care and feeding" of that part of the sewage treatment system.
A "starter" is not needed for bacterial action to begin in a septic tank. Many bacteria are present in the materials deposited into the tank and will thrive under the growth conditions present. The ideal anaerobic bacteria are plentiful in human waste.
Care and feeding of your septic system
If you feel an additive is needed, be aware that some may do great harm. Additives that advertise to "eliminate" tank cleaning may cause the sludge layer to fluff up and be washed out into the drainfield, plugging soil pores. Some additives, particularly degreasers, may contain suspected carcinogens that will flow into the ground water. The disposal field is not designed to handle grease. The septic tank is designed to float grease wastes and hold them in the tank for breakdown into simpler elements that do not float on water.
Send all sewage into the septic tank. Never run laundry wastes directly into the drainfield or a separate pit. Soap or detergent scum will contaminate the groundwater or plug the soil pores.
Normal amounts of household detergents, bleaches, drain cleaners, and other household chemicals can be used and won't stop the bacterial action in the septic tank. But don't use excessive amounts of any household chemicals. Never put antibiotics or quaternary ammonia disinfectants in sewer systems. Do not dump cleaning water for latex paint brushes into the house sewer. There is the danger of plugging the disposal field and/or stopping the normal operation of the septic tank.
Don't deposit coffee grounds, cooking fats, wet-strength towels, disposable diapers, plastic or latex products, facial tissues, cigarette butts, and other non-decomposable materials into the house sewer. These materials won't decompose and will eventually fill the septic tank and plug the system. Ground garbage may find its way out of the septic tank and plug up the drainfield. It is better to compost, incinerate, or deposit the materials in the garbage that will be hauled away.
Avoid dumping grease down the drain. It may plug the sink drain or the sewer pipes. It will build up in the septic tank as a floating scum layer and eventually break down, but it's better to keep a separate container for waste grease and discard it with the garbage.
If you use a garbage disposal type of food waste grinder, it may be beneficial to the operation of the septic tank in the same way it helps in a compost. Moderation is the key, because a small septic tank could become overloaded and you may need to remove septic tank solids more often.
Paper towels, toilet paper and tissues should break up easily if disposed of in the toilet. One way to find out is to put a handful of the paper tissue in a jar half-full of water. Shake the jar, and if the tissue breaks up easily, the product is suitable for the septic tank. High wet-strength tissues are not suitable. Colour has no effect on the septic tank.
Recharge wastes from a properly operating water softener will not harm septic tank action, but the additional water must be treated and disposed of by the drainfield.
If the softener recharge overloads the liquid sewage disposal system, this waste water can be discharged to the ground surface separately, since it contains no pathogens. It should be discharged in a location where it will not be a nuisance or damage valuable grass or plants. Recharge wastes contain salt or the chemical used to recharge the water softener media. Salt has been reported to plug percolation in clay-type soils in the disposal field.
Go easy on the soap
Using too much soap or detergent can cause problems with the septic system. It is difficult to estimate how dirty a load of laundry is, and most people use far more cleaning power than is needed.
It's generally best not to use inexpensive detergents that may contain excessive amounts of filler or carrier. Some of these fillers are montmorillonite clay, which can seal soils. The best solution may be to use a liquid laundry detergent, since they are less likely to have carriers or fillers.
Each septic system has its own capacity
Just as wells have limited capacities, each septic system has a certain capacity.
The disposal field limits the amount of water that will pass through the system in a given time, and the conditions in the tank limit the amount of semi-solid waste. If the solids from the tank overflow into the disposal field, plugging and failure will result. One way to greatly improve the standard septic tank is to fit a filter to the outlet which will give a timely warning that something is wrong before the solids reach the tile field. Users of the system should know the on-site sewage treatment system daily capacity. Each gallon of water that flows into the drain must go through the septic tank and into the soil absorption area.
Conserve water
The following are some ways to conserve water that cause no hardship in anyone's standard of living
Be sure that there are no leaking faucets or other plumbing fixtures. Routinely check the float valve on all toilets to be sure it isn't sticking and the water isn't running continuously. It doesn't take long for the water from a leaking toilet or a faucet to add up. A cup of water leaking out of a toilet every minute doesn't seem like much, but that's 90 gallons a day! Be sure that there is no water flowing into the sewer when all water-using appliances are supposed to be off.
Installing a water meter is one way to know how much water you are using and how much the water use will be reduced by doing certain things. A water meter for a home should cost from $50 to $100, plus installation.
Many toilets use 5 to 6 gallons per flush. Some so-called low-water- use toilets are advertised to use only 3.5 gallons per flush. But the design of the bowl hasn't been changed, and often two flushes are needed to remove all solids. That's seven gallons! Toilets are available which have been redesigned and will do a good job with one gallon or less per flush. Using a one-gallon toilet rather than a five-gallon toilet will reduce sewage flows from a home by about one-third. This reduction may be more than enough to make the sewage system function again.
Front-loading washers and suds-savers use less water than top-loading machines. If your sewage treatment system is reaching its maximum capacity, try to spread the washing out during the week to avoid overloading the sewage system on a single day.
Baths and showers can use lots of water. "Setting up camp" in the shower with a shower head flow of 5 gallons per minute will require 100 gallons in 20 minutes. Shower heads that limit the flow to 1.5 or 2 gallons per minute (and have a full-flow function to allow rinsing shampoo out of hair) are available. The idea is to consider water as a valuable resource.
If you don't use too much water or put materials in the septic tank that bacteria can't decompose, the septic system will be trouble-free for many years. Don't forget, the septic tank does need to be cleaned out when too many solids build up. However, pumping too often will also prevent the tank from working properly.
|
Number Of People Using The System |
|||||
|
Tank size (in gals.) |
1 |
2 |
4 |
6 |
8 |
|
Number Of Years |
|||||
|
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 |
Inspecting and pumping your septic tank
If there are four people living in your house and your septic tank can hold 1,000 gallons, the tank should be inspected and pumped at about every three years.
To properly clean a septic tank, the manhole cover or the tank cover must be removed. A septic tank cannot be cleaned adequately by pumping out liquids through a four-inch inspection pipe. Doing so often results in some of the scum layer plugging the outlet baffle when the tank refills.
Be sure the tank is opened when it is cleaned. At this time, the baffles or tee fittings should be inspected and replaced if necessary.
Rather than pumping the tank, the sludge depth on the bottom and the scum layer on the top of the sewage in the septic tank can be measured by using a cloth wrapped and fastened to a wood pole inserted into the sewage through an inspection hole in the top of the tank.
By measuring the levels and state of materials in your tank, an exact and informed decision can be made on pumping necessity.
Caution: Never go down into a septic tank. The gases present may poison or asphyxiate you. Only trained professionals should enter a septic tank or any other confined space.
* Sponsored by Friends of Cortes Island Watershed Sentinel Fund
* Thanks to: Roger Machmeier, Ph.D, Professor Emeritus, University of Minnesota, and Karen Mancl; Journal of Environmental Engineering, 1984; Vol. 10.
* Thanks also to the Gabriola Ground Water Management Society for providing information and advice.
***
[From WS October/November 2000]