Short and sweet. First, we are on a septic tank. We are in Mississippi.

We called a plumber to snake our drain on our washing machine because one load pours gallons of water onto the laundry room, even caused us to have to replace a brand new washing machine.

Plumber says the old cast iron pipes have become completely gunked up with black sludge that snaking it does nothing. Recommended someone bring a jetter, stand on the roof and flush out the entire pipe.

Note: This pipe connects our washing machine and kitchen sink. If we do nothing, the sink is next.

Problem is, the jetter may or may not work. If it does not work, we will have to run new piping. The plumber suggested just have it run into the yard since it is just the washing machine and kitchen sink, not the toilet.

Running pipe into the septic tank would require going into the foundation, basically a lot more work and a lot more expense than we can handle.

So, is it safe to run the pipe into the yard? Legal? I can't imagine a licensed plumber would tell us to do something that is illegal but you never know. We have children. We are near a lake (hundred yards or less) so that concerns me, too.

Any and all advice is welcome.

5 Answers 5


What you are looking for is the Laundry-To-Landscape system: http://oasisdesign.net/greywater/laundry/

This system works very well and is easy to implement yourself at very low cost. I have implemented it myself and it works perfectly, providing much needed irrigation water to my parched desert yard (not a problem in Mississippi I imagine!). And unless you're washing poopy diapers, laundry is graywater, so it's not a health hazard. You could direct the water to mulched trees, or a gravel-filled trench you could dig. But don't just dump it onto the grass.

  • 4
    you do need to use graywater-friendly detergent, though
    – DA01
    Commented Nov 22, 2017 at 16:54

It's not to plumbing code if it's just discharged onto the yard. If used for subsurface irrigation, it can be a compliant greywater system, with the plants acting as a biofilter. The issue being that the Laundry has potential for fecal coliform (of course, if you wash with soap, most of them will be dead, but that's the reasoning, ignoring that soap and bacteria don't get along.)

Given the "near-lake" location, one more reason not to.

I grew up (happily ignorant of plumbing code, or before that bit was codified) with pretty much the described system (no kitchen sink involved) where the laundry water was usually diverted out the window into the back yard to limit what went into the septic. Nobody died from it, but I would not set it up that way now.

Depending how much the "jetting" attempt is going to cost, either just replace the cast iron with PVC, or try jetting and then replace with PVC if it fails.

  • 3
    Depends on the plumbing code. Out here in the west, what Jeff is looking to do is actively encouraged by the powers that be and permitted by code. And I'm not aware of a single documented case of people getting sickened by laundry graywater.
    – iLikeDirt
    Commented Dec 16, 2014 at 17:43
  • 3
    Grey Water disposal regulations depend on how groundwater in your community is used. In my community, almost half of our municipal water is pumped from groundwater and re-use of grey water to irrigate is illegal. There are certainly regulations for grey water disposal when you are close to surface water bodies like lakes and rivers. Detergent-laden water contains phosphates that when discharged to open water cause toxic algal blooms. Commented Jan 3, 2017 at 19:08

Anyone who fertilizes their lawn or shrubs is probably adding phosphates to their landscape. I checked my laundry detergent, it says "phosphate free". As for "coliform bacteria" I'm sure the bear, water foul and other wildlife add a thousand times more then my washing machine does. I wouldn't put soapy washer water directly into a lake or stream but putting it on the ground, where it will be absorbed, is no different then putting in my septic, ecologically speaking. This probably cuts the load on my septic tank in half, if not more.


Actually, it is foolish to discharge washing machine water into your septic system, considering the wear and tear it will subject your system to as the single largest depositor to it.

Just plumb it outside and use a biodegradable laundry detergent. Of course, a grey water tank and pump would be nice - but not mandatory.

Of course, if you live in California, good luck.

  • 1
    I would be surprised if the washing machine is the largest depositor. Toilets 1-5 gallons per flush, showers, 10-15 gallons each. Washing dishes 10-20 if by hand, somewhat less if you use a dishwasher, somewhat more if you have to pre-wash before dishwasher. Commented Dec 29, 2017 at 23:24

Most States it is illegal to dump greywater directly on the ground. Also, most States that allow the use of greywater, require that the system be designed and built by a licensed plumber certified by the State in Greywater treatment and disposal systemsl just any ole plumber will not due. Greywater must have a filtration system, and disenfection system; you cannot just run it out of the house onto the ground anywhere ( legally ) that I know of.

FYI, per a previous post above, water from the kitchen sink is NOT considered greywater but blackwater.

  • 1
    As someone noted in an above response, sink water is not greywater, but rather blackwater. That is wrong. A sinks waste is considered greywater unless a disposal is hooked to it. No disposal, no Blackwater.
    – Rocket man
    Commented Jan 15, 2019 at 15:54

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