Pipe size for HE washer?

Hi -- I'm setting up a laundry-to-landscape system and have a question about pipe sizing.

We have an HE washer (a few years old) that has a drain tube of 3/4" ID. We are also planning on hooking in to some pre-existing 3/4" PVC pipe that runs under a concrete walkway (a distance of about 12 ft). (This pipe has never been used, and this will be it's designated purpose. If we can't utilize it, we'll probably scrap the whole project, because we don't want pvc pipe exposed on this nice walkway.)

My question is: do I still set up the system with 1" pipe off a 1" 3-way valve, and also use 1" pipe into the irrigation areas? Or should I stick with 3/4" pipe throughout the whole system? I'd hate to blow out the washing machine motor or run into any other pressurization problems.

Thanks.

D Nordland : You have two choices to make this work 1)have your washer pump out into a large utility sink so the water can drain out by gravity through a
3/4 inch system. OR

2) increase ALL your piping up to 1.5'' inside diameter to handle the volume of water pumped through it.

Your washer was (I THINK ) designed to be hooked up to this size drain waste and vent DWV plumbing -with an air break so that the system could never become
pressurized ! You manual should specify this size or bigger - see what it says !

While you could certainly use a garden hose and a piece of 1.5'' pipe to do a little "hydraulic mining"* to tunnel through the soil under your concrete walkway -
that still leaves the problem of the Creating a 1.5 inch hole in your foundation wall.

Actually this is a pretty simple job too but you may need a pro to make it look nice or you could just hide it behind a bush ! For the good of the Craft ! Big AL

* Try a Google search for Hydraulic mining or hydraulic tunneling -images Hopefully a few clicks will get you a good article or aD.I.Y. U-Tube video A.L.

Some washers have enough pump that it could do this as 3/4 all the way, some can barely pump up to the normal air gap and can handle zero additional backpressure.

The rest of the rises and falls and total pipe length and corners all matter. A sketch or wordy description of the total system would help.

- if the discharge hose is thick wall black rubber pipe that has a 180º bend 6'' - 8 " before the end -then I would plan on at least a 1.5'' piping system into a
cistern with a gravity drain ! Again look at your operating manuals set up directions !

30 + years being a Mr. Maytag Repair person and Laundromat owner ! Big AL

Thanks for the replies.

I took a look at the owner's manual for my washer (LG WM2010C) but didn't see any specs for the pump, other than the total height of the drain hose should not exceed 96" from the bottom of the washer. The drain line that came with the washer is a gray, thin, corrugated plastic tube (3/4" ID).

I'll try to explain the details for my planned graywater system. (If not clear, I'll try to post some sketches.)

Washer: HE LG WM2010 located on ground-level on the inside of an external wall.

Inside: I would mount a 3-way valve about 1 ft from the top of the washer, then run a PVC pipe horizontally from the valve for about 4 ft, then out the exterior wall.

Continuing Outside: The PVC pipe would make a 90 degree horizontal turn along the outside wall for about 6 inches, then I would run a vertical pipe (with a T-connector) 6" up for the vent, then about 4ft down (with an inline swing check valve and a disconnect area) where it would meet the existing 3/4" pvc pipe that runs under the cement walkway.

Existing PVC Under Concrete: The 3/4" PVC goes vertically into the concrete about 4" deep, then makes a 90 degree horizontal turn to run the length of the walkway for about 12 ft. There is a 45 degree bend about half way. The 3/4" PVC exits the concrete about 8" from the fence line, about 4" below the top of the concrete. (I assume the contractor that poured the patio would have enured there was some sloping of the pipe. Water appears to be flowing well when we did some testing.)

Yard Irrigation Line (1): From 3/4" PVC extending from the concrete, we want to run a 25ft straight, slightly downhill-sloping pipe with 3-4 outlet areas, then a 45 degree turn for about 8 ft ending at the final outlet area. We will NOT have any trouble maintaining a slight downhill-slope along the entire length of the 'irrigation' line.

Outlet areas: 4-5 outlet areas. Each outlet area will be large mulch basins with bins to keep the pipe elevated. We will drill a number of holes in the pipe at the outlet areas, based on what the flow looks like during testing.

Hope this is clear! Thanks again.

Ok, the 96" maximum head means it can't handle much extra pressure.

If you make that 4 foot piece between the vent and the walkway a large diameter pipe or container it can act as your holding/surge tank. Something like a small rain barrel.

R Scott: Ah, interesting. About what size vertical pipe are we looking at, here? How many gallons would it need to be able to hold at one time?

I found a handy calculator here. http://www.handymath.com/cgi-bin/cylinder.cgi

EX: 6" pipe, 4ft long will store 5.8 gallons

D. Nordlan : Capture Both the Wash water and rinse water as they are discharged/pumped out of your machine and time how much time passes between
your Wash water discharge and your Rinse discharge ! Thats how much time you have to for the 1st load to drain away ! (or increase your holding capacity
by that much !

Also how often will the washer be doing more than one load per day ? Big AL

If you make your more of your external drain pipe the same diameter as the pipe you are attaching to the 3/4 (i.e. 6 inch pipe exiting the house and running horizontally) you could gain that much more holding capacity. You can increase pipe diameter once you exit the side walk as well, that should help get things draining faster as well. I would go for it and experiment a little... I think it will work out fine.

Thanks, everyone. Lots to consider...not sure what I'm going to do, yet. Will do some testing of water output this weekend.

Just fyi... We typically do around 5-6 loads of wash per week. We normally don't do more than 1 load per day, but sometimes 2 loads on a weekend day. To keep everything healthy (pump, sewer pipe, ground saturation, my nerves), and to occasionally use regular laundry detergent, I was planning on diverting every other load to the yard.

Of the washing machines I can remember, I had one that discharged 2 gallons at a time and one that discharged nearly 20. I haven't measured my current HE machine, but guess it is a little over 5 gallons. A 6 inch pipe might do it, but if you price 6 inch pipe you will find a 15-30 gallon plastic barrel is cheaper (on craigslist, anyway) and a can of paint can make it match the color of the house so you don't notice it.