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Septic System Failure! How to Rehabilitate a Failing Septic Leachfield, and How to Check if Your Septic Needs Pumping

Perhaps you already have raw effluent bubbling over the surface, or maybe it's just threatening to.

Or perhaps your local authorities are simply asking that you do a $30,000 overhaul of your system.

Or if you just want to save money and resources by doing the most effective septic system preventative maintenance, and nothing unnecessary.


What to do? Here's effective strategies, in descending order of bang-for-the-buck:

Give the leachfield a rest by fixing leaks

The issue: The relentless, 24-7 nature of leaks prevents the leachfield from ever drying out, which can lead to progressive failure due to the growth of anaerobic biomats, which have about 1/100th the permeability of the soil they grow over (see Long-term acceptance rate).

The cure: Fix all leaks.

Conserve water

The issue: Same as above.

The cure: efficient habits, and efficient fixtures. For details, see our Water Conservation Central. Re-direct the greywater from the septic (see below). Install ultra high efficiency toilets or go withComposting toilets...at which point there could be zero water going into your septic system, giving it a chance to reset, or rendering its performance moot.

Give the leachfield a rest by diverting laundry greywater

The issue: Laundry greywater is about 20% of total septic loading, average. However, it does more harm to leachfields than water from any other fixture. This is because waterlogged lint from clothes is almost the exact density of water, so it is not easily removed by settling or floating in a septic tank, some of it just floats on through. Once at the soil interface, it tends to "paper mache" this interface shut, especially with non-biodegradable lint from synthetic clothes.

The cure: Re-route laundry greywater from the septic to mulch basins in the landscape, for irrigation or just disposal. Our Laundry to landscape  page explains (free) how a handy person can do this in an afternoon, with all on the shelf components. It's also got a list of installers who can do it for you. Our Laundry 2 landscape-video gives in depth visuals on how to design and install a system.

Give the leachfield more of a rest by diverting the rest of the greywater

The issue: Greywater is 60-80% of total septic hydraulic loading, and about half the solids (mostly from the kitchen sink). The relationship between septic loading and failure is exponential. Reducing the load by half could extend the life not by twice, but by several times.

The exponential relationship between load and failure can also work against you. If the load on a septic goes up just a bit, its life can be reduced dramatically. This is not an exact mathematical relationship, but it gives you the idea: Taking water out of the system dramatically extends its life.

The cure: Re-route all greywater from the septic to the landscape, for irrigation or just disposal. Our Greywater central leads to about 100 pages of free info on this topic, and Oasis greywater-book and Builder's GW Guide-book are the definitive works on this topic.

Install a leachfield protector in the septic tank

The issue: When the space in the septic tank between the scum mat and sludge is too small, solids can get flushed into the leachfield.

The cure: A leachfield protector is a screen that you install on the outlet that clogs (cheap repair) instead of letting the leachfield get clogged (expensive repair).

Note that this is more in the nature of cheap insurance. It won't cure an already wrecked leachfield.

Pump the septic regularly or when necessary

The issue: Same as above.

The cure: Pump the solids out of the septic. You can (a) do this on a schedule, or (b), when necessary. How do you know when it's necessary? Check the thickness of the scum mat and sludge layer on a schedule, and have it pumped only when when the space between the outlet and scum/sludge is too small, like less than a foot.

To check outlet-to-leachfield height: this is easy when the tank is freshly pumped, you can just see it. In some systems you can find this height by opening the septic tank access over the outlet and fishing around with an L-shaped rod to find the height of the bottom of the outlet opening underwater between the scum and sludge. Record this relative to to a fixed point on the access opening and write it down, and you won't have to record it again.

To check scum thickness: open the septic tank access at the outlet and push a rod with a 4" L bend to the top of the scum, note the height, then push it through the scum layer, rotate it, and pull back up gently until you can feel the resistance of the bottom of the scum mat. Note the height. Rotate 180°  and try again, note the height. The distance between the top height and bottom is the scum thickness, the bottom of the scum to outlet dimension is the important one; it should be at least several inches. Note these numbers and the date in your house files.

To check sludge thickness: push the rod slowly toward the bottom and note the height of the first resistance; that's the top of the sludge. Push to the bottom of the tank; that's the sludge thickness.

Especially if you aggressively conserve, and have greywater diverted, sludge and scum may accumulate far less quickly than average, enabling you to safely wait much longer between pumpings. I checked our scum and sludge annually for several years. When I'd established that it was accumulating super slowly, I switched to checking every 5 years, and we're still not to the point of needing another pumping.

Note: I often hear "We've never pumped the septic and it's working fine." This is not a good strategy. This equates to waiting until the leachfield clogs, and then pumping the septic...and having to replace the leachfield, a much more expensive proposition.

Note that this is more in the nature of cheap insurance. It won't cure an already wrecked leachfield.

Install a leachfield extension or modification

If your leachfield has failed, install an extension or modification. For free ideas on improved green leachfield design, see:Green septic system.


Good luck!


Where does this information come from? What is our angle?

We are providers of original, accurate, up to date information on ecological living, since 1980. We don't sell septic system components, or do installations (except as part of R&D on new designs). We do wastewater system design, but we are probably too busy to take your project on. We give away about half of our info online, and sell the other half. What we get out of posting hundreds of pages of info for free is that some fraction of you will conclude that our free info is so helpful you'll link to us, which will increase our visitor traffic. Others will conclude that as much as our free information is helpful, buying a books or videos would help even more. Our main strategy to this end is to be accurate and trustworthy. (More onWhy trust this info).


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