No one wants a wastewater pool in the backyard, particularly if they have toddlers around who will splash in anything wet. Wastewater is exactly what you think it is - the stuff you flush and wash down your household drains.

About a third of the homes in North Idaho are in areas where city sewer is not available. These homes are on septic systems rather than city sewer systems. Without regular maintenance, septic tanks can clog and wastewater can bubble to the surface or stick in drainpipes from the house.

Crews that clean clogged tanks have pulled out sunglasses, toys, combs, soap bottles - debris that fills a tank because it doesn't decompose. Remember the doll your toddler flushed down the toilet? It's resting in your septic tank and will stay there until someone pumps it out.

Here's how a septic system works: Wastewater from your house flows into an underground tank where it separates. Solids sink. Light material, such as grease, floats. Most of the remainder - effluent - flows out the end of the tank and travels down a pipe to a drainfield located on the same property as your home. In the drainfield, the effluent percolates into the ground where the soil treats it.

Organic solids in the tank eventually decompose, but other solids don't. Coffee grounds, cooking fats, disposable diapers, feminine products, cigarette butts and more pile up. Pumping them out - or not putting them down the drain in the first place - is the only way to keep the tank working well.

One septic tank pumper said he'd seen granule soaps that don't dissolve build up to the size of a basketball.

Grease is another major problem in septic tanks. Even people who scrape grease into the trash before washing a pan end up with grease building up in their tanks. Wiping the film from the pan before washing helps.

Panhandle Health District (PHD) keeps a list of licensed pumpers in the area. Tanks need pumping about every five years, depending on use. Large families may need pumping more often. Some people pump on a regular schedule. Others wait until it's obvious their tank is clogged.

Drainfields are usually not too far from the septic tank. They're two to four feet underground and need oxygen to work. They disperse effluent over a large area where soil microorganisms help it decompose.

Planting grass or flowers over a drainfield works, but covering it with a building or driveway doesn't. Planting a vegetable garden to grow in a drainfield full of human and other household waste also isn't a good idea.

The expected life of a drainfield is roughly 20 years, depending on use. Solids that make it into a drainfield and don't decompose can ruin a drainfield and cause effluent to rise to the surface. That's another pool you don't want your toddler splashing in.

Eventually, naturally-treated wastewater makes it down to the ground water and/or to surface water. Ground water is used for drinking, which is why it's important not to dispose of chemicals and pharmaceuticals (drugs) down the drain. Not only can they disrupt the bacterial activity needed to treat wastewater, they can also get into the ground water.

Visit www.phd1.idaho.gov and click on Septic Permit search to find out where your drainfields are located. "Care and Maintenance of your Home Septic System" is available at PHD offices in flyer form or on the website under Environmental Health/sewage.

More questions? Call PHD's Environmental Health division at 415-5220.

Cynthia Taggart is the public information officer for the Panhandle Health District. She can be reached at ctaggart@phd1.idaho.gov.