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Snuffy
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# Posted: 2 Nov 2014 06:21pm - Edited by: Snuffy
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I am finalizing plans for our cabin and have a question regarding the plumbing. I plan on connecting the kitchen sink and shower drains together to run the gray water into a soakaway or gravel pit. Since it is gray water only and not connected to a sewer or septic do I still need to vent the system?
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fasenuff
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# Posted: 2 Nov 2014 07:32pm
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Venting not only helps get rid of odor but allows the drain pipe to breath. Without the vent drainage would be very very slow and noisy as the air needed to drain would gurgle slowly through the water.
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toyota_mdt_tech
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# Posted: 2 Nov 2014 07:36pm
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Alwasy vent, this allows the water to drain OK without creating a vacuum. You need to have air to enter behind the water going down the drain. Just make sure you orient the ABS drains properly.. They are more curved and need to curve the right way. The vents dont need the sweeper fittings. The drains do. Most kitchen sinks are 1 1/2" while bathroom and vanity sinks are 1 1/4". We use the black ABS and you want a drop on the line a certain min specs. You do not want it to drain too slow. Too slow or an area where water can remain can collect sediment and also freeze. Lay it out in your head, know where the exit point of the line will be, then design it around that. If the sinks are back to back, you can do it in one vent, but separate locations, they will both need vents. A vent can go through the roof. But there is a special vent that has a cap that can open to draw in air as needed and not vent sewer gas inside. I'd still have it exit in an attic. Some island sinks will have these shutter valve units right under the sink to draw in the air but not spill water. An island where you dont want a vent going upward.
Drain or leech fields are more critical, too steep is also an issue 1/4" drop per foot. But thta is an area you are not dealing with.
3 types. But you dont want these to jsut be inside a wall cavity.
http://smile.amazon.com/Oatey-39012-In-Line-Vent-Black/dp/B000KKSP52/ref=sr_1_fkmr1_2 ?ie=UTF8&qid=1414974890&sr=8-2-fkmr1&keywords=sink+drain+vent+shudder+valve
http://smile.amazon.com/Oatey-39239-Admittance-Installation-Tubular/dp/B000RUL1WY/ref =sr_1_fkmr1_3?ie=UTF8&qid=1414974956&sr=8-3-fkmr1&keywords=sink+drain+vent+shudder+va lve
http://smile.amazon.com/Oatey-39016-Sure-Vent-Admittance-Adapter/dp/B000BVMX62/ref=sr _1_fkmr1_1?ie=UTF8&qid=1414974974&sr=8-1-fkmr1&keywords=sink+drain+vent+shudder+valve
They are called "Air admittance valve"
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bldginsp
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# Posted: 3 Nov 2014 07:11am - Edited by: bldginsp
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I inspect plumbing every day, and agree with what is said above.
Vents prevent siphoning as the water flows, which will pull water out of the traps, allowing stinky gas in through the sink.
Also, they give displaced air somewhere to go as water flows in the pipe.
That said, if your piping is very short, it may work without a vent. If you increase the main drain pipe to 3" with no toilet, there is enough room in a short run to prevent siphoning and move displaced air.
'Air admittance valves' allow air in to prevent siphoning, but don't let air out, so they don't release the displaced air when water first runs in the pipes. they only do 1/2 of the job that vents are supposed to do.
It's a bit of a pain to get a vent up through the roof, but it will ensure that your drain system works well.
Make sure your vent takes off of the drain on top of the drain, downstream of the fixture. Water backwashing in the vent will clog it with soapscum eventually, and if the vent is upstream of the fixture it wont relieve displaced air.
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bobrok
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# Posted: 3 Nov 2014 09:08am - Edited by: bobrok
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I'm going to go out on a limb here and share what I did under similar circumstances. Whether or not this is correct I will leave up to forum feedback, however it has worked very well for me and I am pleased.
We have a shower, bathroom sink and kitchen sink, all of which are surface drained into a small stone filled drywell.
This is a 3 season camp, occasionally used during freezing temps but not occupied over winter. I used std 1-1/2" pvc drain but I did not install traps anywhere. Each drain is simply a 90° connection to the downpipe. I have about a 10" drop over the 20' run of the drain underneath the camp and then about a 25' run on the surface to the drywell. I shallow buried that run to allow me to mow over it and for aesthetic reasons.
My reasoning for doing this was twofold: first, there was no sewer gas or odor to contend with since we weren't sewer connected. Secondly, it insured that I would never have a frozen trap through my oversight or a sudden freeze while the camp was still open.
No traps mean unrestricted water flow and plenty of air to push through.
We are not extreme water consumers either so flow is minimal.
I don't know your circumstances but if similar to mine you could save a lot of work by doing this.
I will edit by adding that my shower floor drain is at a point above where the sinks enter the drain systen and I get no up flow into the shower basin as well.
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bldginsp
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# Posted: 3 Nov 2014 10:27am - Edited by: bldginsp
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bobrok- sounds like a workable system, if totally not to code. So long as your system is not using or connected to any toilet waste, you don't have the worst case scenario of possible health issues. But you will still have some nasty bacteria in your drainfield, so if you ever do start getting backup that's the time to take immediate action. But that's not a function of your plumbing design, it's the drainfield design. All drainfields eventually silt up and then the water back flows.
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bobrok
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# Posted: 3 Nov 2014 10:39am
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Where we are in the Adk park we are required to surface drain. Septics are not allowed, must have an outhouse for solids (Long story, seasonal hunting camps, cannot occupy full time, lotta NYS bureaucratic bull, be glad you don't live here).
We pour good old liquid bleach down the pipes during the year. This helps. And so far with minimal water usage our drywell has never even so much as backed up into the pipe at point of discharge.
Thanks for the tip.
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bldginsp
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# Posted: 3 Nov 2014 12:19pm
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Pouring bleach down it will kill off the bacteria in it altogether. Maybe that's the best thing to do with this type of drywell, I don't know, but in a septic drainfield you don't want to do that because it's the bacteria that digest the bad stuff. The bacteria also eventually cause the drainfield to clog up as the 'bio-matt' gets thicker and larger. So in a septic the bacteria help and hurt, they make it work properly until they eventually make it not work at all if that makes sense. But in a 'drywell' such as this maybe you don't want the bacteria buildup, I don't know. It's more sanitary but then how does the drywell dispose of waste in the water? Maybe it doesn't- you just use the drywell til it clogs up with soap scum and the few kitchen scraps that make their way down there.
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bobrok
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# Posted: 3 Nov 2014 12:42pm - Edited by: bobrok
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Eggs-akly!
If it becomes an issue I can dig a new pit.
We use much less than 1000 gallons of water per season at camp, more like 750 gallons. Not a lot.
Waste scraps on the surface are gobbled up by wild animals.
Ok, let me edit that reply so that you know we don't throw waste down the sink, obviously. We are very careful to dispose of food waste in accordance with the "do not feed the bears" mantra.
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bldginsp
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# Posted: 3 Nov 2014 12:53pm
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I can see the Environmental Health inspector who approved my large septic system ($7,000) producing a little septic in his pants if he perused your description. But then I live in Caliregulationfornia.
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Snuffy
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# Posted: 3 Nov 2014 06:25pm
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Thank you, everyone, for the tips. Bobrok , a system like yours is what I was planning. I couldn't really see a reason to have traps either, if there is no sewer gas to block. I guess I can add a trap and vent later, if it doesn't work for me.
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