washing machine grey water pump?

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andonso

Active member
Joined
Apr 9, 2018
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25
Hello,

I'm wondering if there is a way to pump washing machine grey water (installed in a shed)  into a septic system where there doesn't appear to be enough slope to naturally drain via gravity the grey water into the septic tank.

Either pump straight into the septic or into a large 200 gallon holding tank then pump into the septic tank.

What would be the best type of pump to look for?

I'm uncertain about pumping grey water into a tank destined for the septic.
 

Lou Schneider

Site Team
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Mar 14, 2005
Posts
11,791
Before you get too involved, verify the slope to the septic tank inlet using a garden hose water level.

Run a hose between the two points, raise both ends the same distance above the proposed plumbing (taking into account the depth of the septic tank inlet below ground) and pour water into one end.

If the water comes out of the other end water will naturally drain out of a tank.  You can put something like a 50 gallon drum above ground at the washer if you need to gain elevation.

You can also get attachments that show the water level at each end of the hose:

https://www.amazon.com/Mayes-Level-10309-Water/dp/B00004YZP8

 

Isaac-1

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Dec 3, 2016
Posts
5,858
Location
SW Louisiana
Also keep in mind that a washing machine drain stand pipe is by code set at a height of 30-96 inches above floor level (depending on location), most are at a height of 39-42 inches, therefore most (all?) washing machines can internally pump their drain output up to 96 inches above floor level.  GE specifically states in their installation manuals that the stand pipe must be between 24-96 inches, be 1 1/4 inch in diameter or larger, and flow at least 17 gallons per minute.

This added standpipe height may be enough to gravity drain in your situation.  If not then you can look into a variety of pump options.
 

Lou Schneider

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Posts
11,791
I never knew a washer could pump it's drain water that high, but I guess it makes sense for a basement installation where the drain lines are near the ceiling.
 

HueyPilotVN

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Joined
Jun 5, 2012
Posts
2,589
Location
Lake Havasu City, AZ
I recently installed a washer and dryer in the RV garage for Renae's daughter Kelly.

I initially ran the drain hose into the floor drain for the RV dump.

The washer would not empty all the water during the spin and drain cycle.  I put a 40 inch tall plastic pipe into the drain and moved the discharge hose up to the top and it now works the way it should.

I would have thought that it would drain better when flowing in top a lower level, not so.
 

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andonso

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Apr 9, 2018
Posts
25
We're also going to be installing a shower and a sink so would require a central drain otherwise a washing machine pump by itself might create enough pressure to push water to a 4 inch sewer drain.

I never did bother using a water level which I remember using years ago while working in the shipyards. Looking at the ground points where water drains from the shed and the 4 inch sewer line inlet I'm fairly certain the sewer is at least slightly above the shed and it's drain. 3 in. sewer drains require at least 1/4 in. drop per foot.

Update:

What we did was find a sump pump and install it in the bottom of a plastic tank that was lowered to below ground level. Ran a 3" grey water drain line to the side of the plastic tank , install the sump pump on the bottom of the tank, then run a line from the sump pump over to the 4 inch sewer line to the septic.

Filled the plastic tank with grey water and the pump turns on automatically at around 6" level and off at around 2" water level. The Zoeller sump pump is able to handle up to 1/2 inch solids.

The plastic tank must be around 200 gallons but never actually fills up as the Zoeller sump pump, pumps around 40 gallons / min with a 5 foot head and the plastic tank is only sunk into the ground approx. 4 feet, where the sump pump only needs to push water approx. 4 feet vertically and 10 - 15 horizontally.

Found a good deal on a Zoeller M53-D sump pump for $65.00 from Offer Up. Works great no problems.

 

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