Greywater Gravity Drain Problems

[dude_bro]

Hey guys, I live in Arizona where it is hot as blazes and water is scarce. I made a DIY gravity drain system to reuse water from my washing machine to water my trees. Below is a really well-drawn sketch (haha) of the setup. My problem is that little to no water comes out at the tree! I already have a filter in place (in the tub, on the exterior drain hose). Do I need a vent or something in the drain hose? The tub is 5-6 feet higher than the output at the tree, and the drain hose is 3/4". Thanks for any advice!

 

[Chuck]

Check your washing machine's installation instructions. There will be a maximum rise specified for the outlet hose, typically 100cm, and I suspect you have exceeded this.

Is the drain pipe rigid? If it's collapsable it might need more pressure to open it than your arrangement provides.

Also, you need proper arrangements, e.g. an air gap and a mulch bed, at the discharge end. Without these the outlet will get clogged with roots. I believe that some states require a 'discharge box' at the end of laundry-to-landscape systems but I don't know whether AZ is one of these.

You may also want some sort of overflow fitted to your tank in case the outlet ever does get blocked...

 

[dude_bro]

All great ideas. I do already have an overflow on the tank, along with a valve to divert bleach water loads to the sewer line (not shown in my pic), and the drain line from the tub to the tree is a garden hose that is above ground, so roots won't get in. The tub is filled up just fine from the washing machine drain hose. My problem is that the tub isn't draining out to the tree (or at least barely at all), and the hose isn't plugged, I already checked that. I'm thinking maybe some kind of air suction type problem or something?

 

[Chuck]

My problem is that the tub isn't draining out to the tree (or at least barely at all), and the hose isn't plugged, I already checked that. I'm thinking maybe some kind of air suction type problem or something?

Your diagram shows a section about 2/3rds along the hose that rises then falls again. If the diagram is accurate, this 'inverted-U' section can form an air-lock, which will restrict the flow. Make sure that the hose runs strictly 'downhill' at every point along its length.

How long is the hose? If you think about it like a drain, you'll need a minimum gradient to achieve a proper flow.

 

[Ben-gee]

What is your tub? Does it have a lid?
For water to leave the tub via the hosepipe, air needs to be able to go into the tub otherwise nothing will happen.

 

[dude_bro]

What is your tub? Does it have a lid?
For water to leave the tub via the hosepipe, air needs to be able to go into the tub otherwise nothing will happen.

The tub is a 30 gallon bucket with a lid that has a vent hole in it, so air can get into the tub. Does air need to get into the hose too? Like do I need an air intake/vent at the low point of the drain hose? I'm kind of thinking maybe I should just spend $100 and put a sump pump in the tub...

 

[snowhead]

Does the water flow out the tub without the hose connected?
Is the hose reinforced or layflat, if layflat there won't be enough pressure to open up the hose?

 

[dude_bro]

Does the water flow out the tub without the hose connected?
Is the hose reinforced or layflat, if layflat there won't be enough pressure to open up the hose?

Yeah the tub flows fine without the hose. And actually half the drain line (50 feet of it) is 3/4" PVC and then the second half is a hose. I removed the hose and just checked the 50' of PVC and it isn't draining either, so it isn't a collapsed line. The PVC is at a small slope or level, so I'm mostly relying on the gravity from the 4-5' of lift from the elevated tub.