Plumbing experts: will this work? (Sink drain question)

[brnctt]

We are building a shop on some vacant acreage (no house, no septic) and the drain pipe for a sink is already roughed into the concrete slab. I was going to do a below ground dry well for this single sink, however after we dug the big hole it rained, and after a whole dry week, not a single inch of water has drained out of the hole in our heavy clay soil. Basically I made a pond. This has me thinking I’d rather drain the sink to the surface where it can evaporate rather than making a pit of festering stinky gray water I’d need to pump when it fills up.

I was thinking I’d run the pipe to a pop up emitter about 30ft away from the shop. The problem is the land is pretty flat, and the pipe exits the slab horizontally about 16” below ground. This means that to have a 2% slope for the pipe, it’s going to be about 2ft below ground where I need to drain it.

I can run a vertical pipe at the end of the run to bridge the gap to the ground, and the level of the pop up (I.E., ground level) will still be below the sink and surface of the slab. Probably 2-3 ft below the bottom of the sink if I had to guess, maybe only a 6” to a foot below the top surface of the slab.

Will this system still drain? I realize there will be standing water inside most of the pipe. I could use some perforated pipe for the vertical part at the end and drill some holes in the bottom of the elbow to give standing water a chance to drain. Could also use perf pipe in the last 10ft of horizontal run. It might take a long time in the clay though.

I also realize I’ll likely need to reach down there once in a while and clean it out. That’s ok.

Will my sink drain super slowly with such a small head height?

 

[rlitman]

I think the 2' from basin to pop up should be plenty of fall over 30' to siphon, and the 2' from the bottom right elbow to the pop up is irrelevant. But you've drawn a gigantic water trap that is going to be festering perhaps as badly as the pond of a drywell you wanted to avoid. Also, if there's a possibility of freezing, that pop up might fail.

What about a compromise with the dry well directly under the pop up? It's probably also a terrible idea, but I'd like to see what the hive mind here comes up with.

 

[bb29510]

dig a big hole. fill with gravel

 

[The Cobbler]

your proposed system will clog continually. the solids have no way to drain, they will settle out in the horizontal run.
use a laundry pump at the sink and it will work(better) because of the pressure

 

[brnctt]

i actually tested it today and it works beautifully. Kept up with a garden hose with full flow, which is more than the sink will ever see. Now I just need to figure out how to keep the “giant P trap” from going rancid between uses. Again, my problem is the clay holds water and doesn’t percolate.

Maybe it doesn’t even matter? Could just flush it out every once in a while by running a few gallons through.

Or I could just drill some holes in the bottom of the elbow. I’m abandoning the vertical pipe being a perforated pipe because the silt would eventually make its way into the pipe and clog the elbow.

Here’s my test setup. You can see my previous idea. Would have been stellar if the soil drained! I just don’t want it to turn into a holding tank for 100+ gallons of disgusting water.

 

[brnctt]

your proposed system will clog continually. the solids have no way to drain, they will settle out in the horizontal run.
use a laundry pump at the sink and it will work(better) because of the pressure

Hmm, how about instead of an elbow at the end, a T? That way the solids could fall at the end. Even if my soil doesn’t drain at least they’d be consolidated in one spot so I could clean it out once in a while.

 

[brnctt]

Hope you guys like my MS Paint skills.

What about this? The idea is 6” of pipe below the T, capped, with holes drilled in the cap, so I could stick a shop vac down there if it ever gets clogged.

The idea is to get most of the water to the surface where it can evaporate and not create an underwater cesspool. Trying to keep the volume of the system to a minimum.

 

[brnctt]

your proposed system will clog continually. the solids have no way to drain, they will settle out in the horizontal run.
use a laundry pump at the sink and it will work(better) because of the pressure

Wouldn’t the pump stop pumping once it stops seeing water though? I think when you use one in a basement or something, there’s always water in the vertical exit pipe. It’s just held with a check valve.

 

[The Cobbler]

i think your plan will be prone to blockages

 

[T45]

i think your plan will be prone to blockages

+1 ... This also reminds me of those pasta pot faucets, lots of horizontal pipe,
very little use. Ends up lots of work prep/post flush, etc.

 

[brnctt]

Then any ideas guys?

 

[Dig Doug]

You need a leach field. Google it to get up to speed

over dig the drain line by 2-3 ft

if your drain line is 12inch below the ground, then dig the leach field 3 to 4 feet deep fill up w/ rock to the bottom of the pipe install pipe w/ holes so water seeks out the bottom of the pipe and into the rock ( leach field)

The idea is to spread out the water discharge over a wide area and have it soak in and go down.
keep in mind if not done correctly or you do to small of a leach field your sink won’t drain.

you don’t want your leach field in bottom of a valley or have water run off to flow into your leach field
pay attention to where the water flows On your property - Water travels at the path of least resistance

NOTE -
This may be NOT to code in your area…

 

[i4ni]

Grey water has to go to septic here. Code. They used to allow a lined evaporation pit.

 

[scfoxman]

Using a vertical pipe at the end could help bridge the height difference. It might drain a bit slowly, but as long as water keeps moving, you're on the right track.

 

[Mr onetwo]

put a solids interceptor under the sink, very common for scullery sinks, ect. Will keep your drain water pretty clean.Then put a small leach field in https://www.zoro.com/jay-r-smith-manufacturing-solids-interceptor-075-gal-2-pipe-871-t02/i/G1829998/ https://tinyshinyhome.com/gray-water-septic

 

[bb29510]

it grey water, there should be no solid, it can legal be ran out on the ground, it can daylight out to a ditch if you have one. Untreated graywater shall not be used to irrigate root crops or food crops intended for human consumption that come in contact with the soil Greywater is water that has been used for washing dishes, laundering clothes, or bathing. Essentially, any water, other than toilet wastes, draining from a household is greywater. Although this used water may contain grease, food particles, hair, and any number of other impurities, it may still be suitable for reuse Ponding or runoff is prohibited and shall be considered a nuisance. Graywater may be released above the ground surface provided at least two (2) inches (51 mm) of mulch, rock, or soil, or a solid shield covers the release point. Other methods which provide equivalent separation are also acceptable.

 

[LOW1]

Are there any state or local health, plumbing or building codes which apply to your situation?

 

[rlitman]

Wouldn’t the pump stop pumping once it stops seeing water though? I think when you use one in a basement or something, there’s always water in the vertical exit pipe. It’s just held with a check valve.

Yes, however the pump flow has enough velocity to scour the pipe clean. That's why the pipe diameter needs to be matched with the pump GPH. Bigger pump means bigger tube. But in your case you're looking at gravity flow. That works in a sewage system that's primarily full of air, but fails once the pipe is flooded. And you cannot simply make the pipe smaller to increase flow velocity, because that increases friction losses, reducing flow on top of the fact that a smaller pipe takes less to clog.

Cobbler hit the nail on the head.

And the T at the far end doesn't really help much if the pipe stays flooded. You really need that T to exit to something that drains the pipe at least most of the time.

 

[nmk_61802]

If you are set on doing it this way vs adding actual septic, the proper way to do it is install an exterior basin with a pump. Pump to ground/ surface outflow, or to a designated sprinkler system. Installing traps inside as per typical plumbing system.

Edit to add: I would guess you could also do it with and interior basin/ receptor as well if that is more to your liking.

Second Edit to add: Best to check with local AHJ, many will not allow surface discharge of grey water as other posters have mentioned.

 

[Mr onetwo]

it grey water, there should be no solid, it can legal be ran out on the ground, it can daylight out to a ditch if you have one. Untreated graywater shall not be used to irrigate root crops or food crops intended for human consumption that come in contact with the soil Greywater is water that has been used for washing dishes, laundering clothes, or bathing. Essentially, any water, other than toilet wastes, draining from a household is greywater. Although this used water may contain grease, food particles, hair, and any number of other impurities, it may still be suitable for reuse Ponding or runoff is prohibited and shall be considered a nuisance. Graywater may be released above the ground surface provided at least two (2) inches (51 mm) of mulch, rock, or soil, or a solid shield covers the release point. Other methods which provide equivalent separation are also acceptable.

if you don't mind me asking...where did you pull that quote from.Totally illegal in my state.

 

[bbrz]

Illegal in every state. I'm not only a plumber, but plumbing inspector in a state that has the most stringent codes of any.
I have never understood why anyone that has shop sinks, or bathrooms will willfully contaminate the soils on your property.
Oils,grease, piss? Don't even try to tell us Oh no that won't happen. Plan ahead and do it right within the codes of your state.
You are not going to live on that property for ever. Who knows what the next owner will put down those existing drains.
Do you have wells that you drink from? Your neighbors? Ever heard of the EPA?

 

[brnctt]

We’re starting on the house next spring, so I’ll just tie it into septic at that time. Thanks all!

 

[bb29510]

if you don't mind me asking...where did you pull that quote from.Totally illegal in my state.

calforina health code, it was a cut and paste

 

[bb29510]

Greywater Codes and Policy - Greywater Action

Greywater Codes and Policy Quick reference for state codes: Arizona, California, New Mexico, Oregon, Washington (Text on this page is an excerpt from © The Water Wise Home: How to Conserve, Capture, and Reuse Water in Your Home and Landscape, by Laura Allen ) Codes and Regulations Understanding...

greywateraction.org

 

[bluedog225]

I had 3 clay holes and two with light sand. Maybe dig some more holes? Or go a deeper?

My sand was under 1.5’ of clay.