washer drain questions

Hello everyone - I am new to this forum. I did some plumbing work for my uncle (for about 3 years) - just long enough to feel confident about my work but not long enough to always know proper piping.

I have two septic tanks - one large one for the house waste and another that only the laundry was going to. I am installing a new washer hookup and it will now be on the 1st floor. The old hookups were in the basement. I will use 2"PVC and I am piping this to the separate septic tank independent from all other drains in the house. The laundry will be the ONLY thing going into this separate 4" leaving the foundation. When it was in the cellar there was no vent.

1. Do I need a vent now? If so, is there a way to do this without exiting the house? - like a loop above or the device type. Venting outside will not be easy unless I run along the 1st floor ceiling through the neighboring closet and out the side of the house.
2. I built the 2" trap already using long sweep 90's (too much water in the trap?) and then an 8" piece of pvc and then another 90 turning down and going through the floor. It looks somewhat like a large S trap. Is this OK?

Thanks for any help, Tom

Looks like trouble in River City.

Your trap does sound like an S, which will be quite likely to self-siphon. Where is that trap? It needs to be on the first floor, with the washer, above floor level. A standpipe rises from the trap, and the machine drains into the trap.

Hard to figure whether it was vented before, if not why not.

An air admittance valve ( Studor Vent) is not a good idea, especiall for a washing machine. The AAV will deal with the trap-siphon issue, but does not deal with positive pressure which can occur with a pumped device like a washer.

Thanks for the reply..............

I was going to locate the trap about 12" off the floor (above the 1st floor).
I rebuilt the trap using 3 long sweep ells (all connected by 3" pieces of 2"pvc), then a horizantal 8" pipe to a tee which would go down through the floor to drain and up to vent (but again vent where?) The closet is in the center of the house.

What is the signifigant differance between a P trap and an s trap anyway? And can I vent through the side of my house which would be about 10' off the ground?

The machine was piped directly into the 4" sewer with just a p trap and no vent. I never had a problem with siphoning. Am I more likely to now that I am further away?

PS - I was thinking that the 8" piece before the tee might make my trap considered a P trap??

washer is coming tomorrow morning and I am running out of time............so - I redid everything and have a tee ready for "some type of vent". The distance from the trap ells (center) is now 10" from the tee so I should have a true p trap. I lowered the trap a bit to 10" above the 1st floor and the standpipe is 27" long/ 38" above the floor. Hopefully an aav will work out and save me a ton of aggrevation and joist notching (ouch!!)

tomfmal said:

I am piping this to the separate septic tank independent from all other drains in the house. The laundry will be the ONLY thing going into this separate 4" leaving the foundation. When it was in the cellar there was no vent.

1. Do I need a vent now?

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In your previous setup, was your washing machine dumping into a sump with a pump sending the discharge on out to the septic tank? And, are you very sure there was/is no vent anywhere?

The tapering-off nature of a washing machine's discharge at the end of its final spin cycle makes it virtually impossible for a standpipe's trap to be either blown dry by the washer or siphoned dry by its discharge, but that septic tank must be vented somewhere and somehow to be sure your washer's discharge does not meet any resistance on its way out, and to be sure the septic tank cannot ever "burp" back into your house. If someone had previously rigged a sump pump to go out to the tank, that might explain the absence of trouble in spite of there being no vent. But yes, I would say you definitely need one now.

Also, and especially when discharging a washing machine into a septic tank, here is a (yellow) filter I use at the discharge end of my septic tanks to keep all the lint and whatever other solids out of the drain field:

www.gag-simtech.com/passive_filters.htm

Thanks leejosepho,
Here the septic situation. I have one old system with a main tank and an overflow tank. Each tank is a seepage tank. I am on long island and because it is sandy they don't use drain fields. At some point (I assume when the main tank was not handling the laundry of a large family - 5 kids before us) a second line was added. We have only been in this house for a little less than two years and I don't yet know where this new tank is. There is also no external vent near the house, like the main has. Anyway there was no sump.The washer just dumped directly into this 4" line which is about 4' off the basement floor. There was only a trap and standpipe. The main house system has a 3" stack going all the way to the 2nd floor bath, which is doubling as a vent for the 1st floor bath (which I know is wrong as well, but working). I moved the discharge into the main 4" shortly after we got here because the tanks were full and we had them emptied,areated, and treated. I figured I would try the laundry in that drain. Unfortunately it was only a little over a year and both tanks were full again. This is why I now feel like I need to use the second system dedicated for the laundry. I can't afford a new main system at 4K right now.

tomfmal said:

I have one old system with a main tank and an overflow tank. Each tank is a seepage tank. I am on long island and because it is sandy they don't use drain fields.

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"Seepage tanks" sounds to me like what I know as "dry wells", and since drain fields have larger footprints, I do not understand what advantage your type of system might have. Also, I cannot imagine dumping sewage directly into a dry well and expecting it to work for very long, but, regulations and practices do vary from state to state, community to community and so on.

tomfmal said:

At some point ... a second line was added ... I don't yet know where this new tank is ... I moved the [washer] discharge into the main 4" shortly after we got here because the tanks were full and we had them emptied, areated, and treated. I figured I would try the laundry in that drain. Unfortunately it was only a little over a year and both tanks were full again. This is why I now feel like I need to use the second system dedicated for the laundry. I can't afford a new main system at 4K right now.

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If I am understanding rightly here, the washer was previously on that separate system, and now you are putting it back there, correct?

I understand "emptied, areated, and treated", and periods of dormancy can also be effective (or at least helpful) along that line. So, you might find that second system able to again handle the washer for a while, but it will likely fill up again.

Do you know how to use a steel rod to follow that "new line" away from the house and locate your second system?

Yes I think the septic service tech called them dry wells. I think it is common here.

"If I am understanding rightly here, the washer was previously on that separate system, and now you are putting it back there, correct?"

Yes that is correct. I don't know how to use a steel rod to find the new tank but I sure would like to know where it is - I assume it is just another dry well. The only reason I suspect it is new is that the 4" is plastic as far as I can see.

What is your thought on the vent? Any problem at least trying an aav ? I will remodel the upstairs later this year and might very well be able to get a vent through the roof at that time.

Can I put the vent directly over the Tee on the 1st floor that the trap will go to?
Thanks!

tomfmal said:

I don't know how to use a steel rod to find the new tank but I sure would like to know where it is - I assume it is just another dry well.

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The pros use a piece of smooth steel rod about 3/8" x 4', and with about a foot of something larger fastened as a T-handle at the top. Personally, I have a piece of 3/8" rebar, a two-pound hammer and a few scars between my thumb and forefinger. Either way, the idea is to gently poke into the ground and find/follow the pipe to wherever it goes ... and you should eventually find yourself poking the lid or top of something much larger. At that point, you should be able to do a little digging and find an access. Subject to however you deal with folks at your local permit palace, I would locate whatever is at the end of that line and consider some kind of expansion before it is again saturated.

tomfmal said:

What is your thought on the vent? Any problem at least trying an aav?

Can I put the vent directly over the Tee on the 1st floor that the trap will go to?

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I do not know what an aav is, but you do need an open, either-way vent somewhere for allowing the tank to "burp" without doing so inside your house. And, running a line from that tee to the outside would seem to me to do the job.

an aav is an air admittance valve - studor type. I know that they are not recommended for washers but it seems better than nothing (like I had). Yes?

I can run a vent up and out when I get the upstairs torn out................

An AAV is like a check valve which allows air in the drain when the pressure is reduced (creates a vaccum) as the liquids flow down the pipe. Works much like an anti-siphon valve on a hose pipe bibb.

Randyj said:

An AAV is like a check valve which allows air in the drain when the pressure is reduced (creates a vaccum) as the liquids flow down the pipe. Works much like an anti-siphon valve on a hose pipe bibb.

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Thank you. I long ago heard someone talk about a "pop up" vent that could be fitted under a sink, and I have seen those kinds of things on shelves in plumbing departments. However, the last one I ever looked at seemed to me to require too much vacuum to open, so I have categorically dismissed them from my own "engineering" considerations.

tomfmal said:

I know they are not recommended for washers but it seems better than nothing (like I had). Yes?

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I would guess it is marginally necessary (even if required) and cannot do any actual harm, but neither will it stop your system from burping back through your trap. So yes, as soon as you can vent to the outside ...

You keep referring to "burping" . Remember, there is no raw sewage going into this dedicated tank - ONLY laundry (gray water). Am I likely to get any burping effect from this??

Gray water or black is not the issue here. Rather, this is a matter of simple displacement:

Suppose your dry well will hold 500 gallons of effluent when full (or 66.84 cubic feet of air when empty) and you pumped 500 gallons into it. That air has to go somewhere.

If a code requires a vent close to your washer trap, then by all means install one. However, at least one way *any* vent is going to keep *any* trap working correctly is by relieving the pressure of displacement going into an otherwise-non-vented septic system.

Now yes, 30-or-so gallons of water occasionally going into an empty drywell might not make any earth-shaking burp, and maybe that four cubic feet of air it displaces would not even be audibly noticeable next to a washing machine still trickling out a little water near the end of its spin cycle. However, the vent you need the most will assure your system can "breathe" a bit, either in or out, when necessary.

Along with all of that, I have heard that venting the far end of a septic system can help maintain it by allowing some oxygen into the digestive process, and I have my field systems vented for that reason. In other words, a smoke bomb in my back yard could theoretically show up through the "smoke stack" at the peak of my roof!

I'm not doubting the need for a vent - that is why I am doing so much research and asking so much advice from as many people as I can. However, I am not finding anyone who knows the code/needs of venting using a dedicated system for the laundry. I am sure that 99.9 % of homes are dumping there laundry into the same septic as the black water. It seems that my case is unique and that the regulations may not be as demanding - but I don't know this as yet. In any case until I know more, I will use an aav and then later run up through the roof. Thanks for your advice.

tomfmal said:

I am not finding anyone who knows the code/needs of venting using a dedicated system for the laundry ...
It seems that my case is unique and that the regulations may not be as demanding - but I don't know this as yet.

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I do not remember whether I said this before, but I also have a separate system for gray water (washing machine and bathtub discharges). The kitchen sink and toilets go into the regular septic system, and the bathroom sinks go there also because I do not want bacteria killers such as toothpaste, mouthwash and peroxide in the gray-water drainage field. Overall, however, both systems are vented the same (and actually in common), where each is able to "breathe" while either accepting or leeching liquid and so that no gas, odor or whatever can come back into the house. In other words, first the overall *system* is vented, then certain traps may need extra protection. Even if neither of us ever find specific "codes" for separate gray-water systems, sound engineering would logically suggest the actual mechanics of their plumbing would be no less than for a regular system.

Apart from all of that, and speaking from at least a little personal experience, home-spun gray-water systems can be problematic because of the lack of bacteria or enzymes or whatever else -- I am no chemist -- to help keep the ground open and receptive. I split my gray water off to reduce the load on a small and old septic system, and I actually even have two of those. But because I have been able to only find out very little about how to make a gray-water leech field "trouble-free" -- Keep the lint out, at the very least! -- I made a drain field big enough that over half of it has yet to even get wet.

So then, you vent plan is fine, but we both need to learn and do more if we want our gray-water systems to work well and to keep on doing so.

PS: Trace that newer line and find out where it goes just as soon as you can. When my wife and I first got this place, I thought it was really neat that the basement sump (for the washing machine) had its own line going out and into the ground ... then I discovered it led to nothing more than a piece of perforated pipe laying just under the surface alongside the garage. The fact that your pipe is not vented leads me to suspect somebody before you might have done something similar.

"great barrier reef" I never thought of that. I would not put it past the previous owner. The 4" leaves the cellar at about 3' from ground level. What are the chances that I will really find/feel something along the way? If it does just go to a perferated pipe that is 3-4' down how will I ever find it?

Thanks for all your great knowledge in helping me to brainstorm my issue.

tomfmal said:

If it does just go to a perferated pipe that is 3-4' down how will I ever find it?

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Using a steel rod as a probe, begin at the house where you know you should be able to poke around and find/feel/hit the pipe, then keep poking and probing while moving a foot or two at a time until you determine its initial direction. It might go straight out from the house for a way, or there might be a 45- or 90-degree elbow just outside the wall or anywhere else along its run to wherever it might go. If after following the pipe for a distance it suddenly drops off your radar and you cannot find it turning off in yet another direction, you might have just found its end and a few minutes' digging at it last know location should answer that question. Hopefully you will find something more than the end of a pipe, and hopefully a little maintenance or "repair work" will leave you with a long-functioning drain for your washer.