What is a Leech Bed?

When we purchased our house a couple years ago, our very nice sewer inspector (who, in my opinion, loved his job more than was physically possible) informed us that the house’s 30 year old septic tank and leech bed was no longer functioning properly and would have to be replaced ASAP. That led to a couple questions:

1. What the hell is a leech bed and why does it go bad?
2. Can the seller put in a new one before we buy the house?

As far as the first question goes, a leech bed (or leech field or drainage field), along with a septic tank, forms the sewer system for houses that are not on public or private sewer lines. A septic tank is typically 1,000 to 2,000 gallons in size and is made out of concrete, fiberglass or plastic (ours is concrete). It’s installed underground and is connected to an inlet wastewater pipe coming from a house. Waste flows out from the house into the septic tank. The tank provides an “anaerobic bacterial environment” and decomposes the waste that is sent to the tank via the house’s toilets, sinks, and showers. Mmmmm.

The basic gist of a septic tank and leech bed
Of course, a 1,000 gallon tank would fill up quickly if the water running from the house didn’t have anywhere to go. So, excess waste water is purged from the tank and cleaned via a leech bed. The purpose of the bed is to:

...remove contaminants and impurities from the liquid that emerges from the septic tank. This is typically done by burying perforated pipes in trenches and allowing the liquid to leach out and the surrounding soil absorbs the unwanted waste.”

If treated with love, septic systems generally have a life expectancy of 30-50 years, although a number of factors can lead to their early demise.

1. Food disposals are a huge no-no (our inspector was all over this – telling us in great detail the horrors of disposals at least a half a dozen times). Basically, disposing of food into septic tanks can quickly fill, clog, or overload the system.
2. Oil and grease from cooking or other activities have a nasty tendency to clog drains and ruin the ability of the soil to filter waste water.
3. Flushing non-biodegradable items down toilets (I’m sure you can think of a few – although alligators probably count as biodegradable) can fill or clog a septic tank.
4. Similarly, the anaerobic bacteria in tanks really don’t appreciate pesticides, herbicides, or stuff like paints and solvents. That stuff will greatly reduce the tank’s ability to decompose waste.
5. Tree roots and other structures can damage a tank or the leech field.

But even with the best care, oils and bacteria will slowly enter and degrade a leech bed and its effectiveness to drain and clean waste water. Eventually, the drain pipes in the system will become clogged, which can lead to sewage backing up into the tank and (if you’re really unlucky) backing up into the house itself.

An actual sewer system installation

While we left the installation of our new leech bed to the professionals, with the proper skills and equipment, it is possible to install one yourself. Here is a forum discussion from someone thinking about rebuilding their leech bed. And, if you’re really adventurous, here is a site that goes through installing a sewer system yourself, down to every last dirty detail. Of course, I only made it a few paragraphs into the article (soil classifications? What?) before my brain starting hurting.

Want to know even more about sewer systems? Who doesn’t? Check out Wikipedia or the EPA.