Ventless drain to daylight

Our home has a well and a septic system. We have a sediment filter in the basement that backwashes a substantial volume of water at 11 gpm into the septic system. We're very rural with plenty of space on our own land, and I'd like to reroute that backwash flow to daylight instead of into the septic system.

There's already a 1-inch pipe stub that runs through the basement wall, coming out 2 feet below grade outside (our frost depth here is 18"). I'm planning to use that stub as the means for the backwash drain to exit the house. The daylight exit would be 225 feet away, with a drop of 6 feet over that distance. I'm considering using 1-inch PVC for the 225 foot run.

The entire drain pipe will be buried below the frost depth. It's the daylight exit I'm trying to figure out how to keep from freezing over. Without a vent in the system, it seems like I might have a slow "glub.... glub... glub..." continual draining after the backwash valve has closed, like pouring from a Coke bottle. If that slower draining goes on for a long time, it seems like ice could build up at the exit and eventually block it, much like ice dams on a roof. I also wonder if we'd hear glubbing noises for hours in the house. My wife would just love that.

I've wondered if putting a dip or trap in the drain line about 10 feet back from the exit would help. Maybe then the water in the last 10 feet would trickle out quickly, and the water behind the dip/trap would remain in the pipe below the frost line until the next backwash.

Should I run the line straight and not worry about ice dams or glubbing? Should I put a dip or trap near the end? Or am I just asking for trouble no matter what I do? Thanks for any advice.

Thoughts...

Put a pit filled with gravel at the end of your long pipe so the water can drain into that. It will be like a mini septic field.

Consider a method where if the pipe becomes clogged, the water bypasses through a check valve into the septic system. I am considering a Jandy valve for the purpose of switching or allowing both paths to be open.

Edit: Maybe consider an additional higher exit which could spew water a few feet off of the ground if the long pipe got frozen shut, and could serve as a vacuum release, as suggested by hj, when the pipe was not clogged.

It would probably NOT "glub, glub", but rather just retain the water inside the pipe where it would freeze. Install a "vacuum relief valve" at the high point where the pipe leaves the house so the water can drain out naturally when the backwash ends.

Reach4 said:

Thoughts...

Put a pit filled with gravel at the end of your long pipe so the water can drain into that. It will be like a mini septic field.

Consider a method where if the pipe becomes clogged, the water bypasses through a check valve into the septic system. I am considering a Jandy valve for the purpose of switching or allowing both paths to be open.

Click to expand...

Thanks for the suggestion. I also have floor drains in the basement, so I can quickly attach a hose and backwash into those if necessary. I would do that permanently, except that it's too cumbersome to have pipes or hoses running across the basement floor.

Where do the floor drains run to?

hj said:

It would probably NOT "glub, glub", but rather just retain the water inside the pipe where it would freeze. Install a "vacuum relief valve" at the high point where the pipe leaves the house so the water can drain out naturally when the backwash ends.

Click to expand...

I like your concept, although I'm not familiar with vacuum relief valves. I looked a few up and can see how they could work in theory. My reservation is that I don't know if it would open at 3 psi (about 7 feet of head) differential, and whether it would stay open for the entire pipe to drain (the pressure differential would continually drop as water drained). I'd also prefer to avoid mechanical devices, if there's any way to get it done with just gravity and pipes.

I've tried a backyard glub test, but I only have a 10-foot section of 1-inch PVC to work with so far. I capped one end, filled the pipe with water, and covered the other end with my hand. Then I laid the pipe with the open end about 3 inches below the capped end and removed my hand. All of the water drained out without any problem. From that, I've been assuming that at least the last 10 feet of pipe would drain completely. Anything upstream more than 10 feet from the exit is buried deep enough not to freeze.

The problem is if the last 10 feet keeps getting new water slowly from upstream. That's where I invented my "glub" scenario -- and I can't test it without assembling 225 feet of pipe. Maybe it's worth doing that as a test run before I trench and commit. If things don't work out, I'm out the cost of the pipe and the testing labor, but at least I haven't trenched in vain or buried the wrong design.

Thanks for your help and ideas.

hj said:

Where do the floor drains run to?

Click to expand...

They join to a 4-inch pipe running to daylight, just to a different exit point. I've tried to figure out how to tie into them, but I've given that up. They run under the basement slab to another side of the house, then under a brick landing and brick stairs, then under my wife's garden... They're also about 7 feet below grade until close to the exit point. Getting to that pipe still means a lot of new buried pipe and is not an easy project.

If I'm missing something in your question, please let me know. It's a good thought to consider -- I just couldn't figure out how to make it feasible. Thanks.

A vacuum relief valve opens IMMEDIATELY and stays open until a pressure flow closes it.

You might want to consider some type of air gap to prevent the possibility of cross contamination.

I would bury a 3" drain to daylight with cleanouts every 50', and then I wouldn't need to worry about it AND it could be rodded or jetted if the need ever arises.

Thanks for all of the suggestions. I'm making several changes based on what I've learned here. First, I've decided to increase my pipe size to 1.5" (I can't manage 3" for this project). Second, I'll put a Tee in the drain pipe up near the house with a stub capped and buried. That way I can add a vent sticking up out of the ground if it turns out I need one.

With the 1" pipe, I had been concerned that water would be forced out of the vent since the 11 gpm flow rate would cause a small pressure buildup in a 225-foot run. Maybe using 1.5" pipe will reduce or eliminate that issue. If the pipe were to get clogged downstream from the vent, however, then the vent would become the new drain exit, with 50 psi of pressure driving water out of it. I'd just have to be careful about vent placement and aiming to deal with that possibility.

So I'll try it without a vent at first, then add a vent if that doesn't work well enough. Thanks again for the help.