Q: I recently moved from a house on a city sewer system to a rural retirement home that has a septic tank. What can you tell me about septic tanks? At my last home, I had clogging issues in my main drain pipe. What are some best practices when it comes to drain lines in any house, and how does one keep them flowing well at all times?

A: Water and solid waste should normally flow to the sewer or septic tank without a problem, assuming your drain lines have been installed properly and with the correct amount of slope.

In my opinion, the ideal slope of a plumbing drain pipe is 3/16 of an inch of fall per foot of run. Some may think more slope is better, but if you have too much slope, the liquids can outrun the solids as they move down the drain lines. You don’t want this to happen, because solid material sitting in a drain pipe can turn into a clog.

Municipal sewer workers and septic-tank pumpers would probably tell you that grease is their biggest challenge. You would be doing them — and yourself — a favor by using paper towels to remove as much grease as you can from your dirty pots and pans before washing them. (Put the grease-soaked towels in your garbage.) This will help to minimize the grease that gets into your plumbing drains.

Some grease will inevitably make it through, however. You can buy products that contain active bacteria that will start to eat the grease that may be coating the insides of your pipes. These bacteria will also prevent septic-tank leach fields from getting clogged with grease.

To keep the drain lines flowing at my own home, I do a couple things.


Each week, I pour 10 gallons of water as fast as possible into the highest toilet in my house. This water creates a vigorous flash flood within the pipes — especially the horizontal drain pipe below my basement floor — and will carry just about everything out of the pipes.

Then, about once a month, I pour about 15 gallons of very hot water down my kitchen sink. Hot water does a pretty good job of dissolving grease, and this action can serve as an alternative to buying the bacteria product that eats grease.

Septic tanks are like magical boxes, as long as you use them correctly. Ideally, the only things that would enter a septic tank is what comes out of our bodies and any tiny food scraps that make it past a kitchen sink strainer.

Mother Nature then takes over inside the tank. Natural bacteria start to eat the waste. When a tank is operating as it should, 1.6 gallons of water enters the tank each time you flush a toilet, and the same amount of partially treated wastewater leaves the tank on its way to the leach field.

In most cases, a leach field is a network of pipes where wastewater is distributed to an area of well-drained soil that’s very sandy. The water seeps out of holes in the pipes and enters the sandy soil. Here, other bacteria and oxygen work to purify the wastewater.

You never want to put chlorine bleach, or any product containing it, into a septic tank. Bleach is so strong that it can kill the bacteria that eat the waste. And don’t ever clean paint brushes inside a house and allow that water to enter the septic system.

It’s important to have the septic tank pumped every two or three years. You’ll need to know the location of the hole that gives the technician access to the tank.

Tim Carter has worked as a home-improvement professional for more than 30 years. To submit a question or to learn more, visit AsktheBuilder.com.