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Small Cabin Forum / Off-Grid Living / Using the septic tank for outhouse
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Sylvan
Member
# Posted: 11 Aug 2020 10:52
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Does anyone know if you can put an outhouse over the manhole cover of a septic tank. We will have a traditional septic and drain field. We do not have a structure yet, or a well. Our excavator says we can put a small toilet right over the tank for now and make "direct deposits". We do not live there full time. My question...won't it just sit there in the concrete tank? Will there be odor issues? We could try venting but I think that only works if the outhouse is getting at least some sun to encourage the air flow. (Our septic will be in the shade) I know we can just dig an outhouse, which we may end up doing but just wondering about the above scenario. Thanks.

hueyjazz
Member
# Posted: 11 Aug 2020 11:41
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You need flow of water to make it work the way it should. I think you would just be filling up a tank you would need to get pumped out when you do want it to work right.

jhp
Member
# Posted: 11 Aug 2020 13:48
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The whole tank is supposed to be watertight, keeping contents in and rainwater out. Your outhouse idea would let a ton of rainwater in and probably overwhelm the drainfield in a big storm. Also I don't think you could ever get enough venting to vent a chamber that big fast enough.

I am guessing your excavator meant just direct connect the toilet to the inlet pipe and fill and flush that toilet manually if you don't have a water line there. That would work the same as if it was in the house, the water in the trap in the toilet keeps gases out.

Brettny
Member
# Posted: 11 Aug 2020 16:46
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The septic tank is where you want solids to stay. Since I assume your going to put liquids in there too you will basically have a holding tank. Just like a porta potty. You will have to get it pumped more often than with a leachfield but it will work fine.

ICC
Member
# Posted: 11 Aug 2020 17:30 - Edited by: ICC
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Quoting: Sylvan
. We will have a traditional septic and drain field. We do not have a structure yet, or a well. Our excavator says we can put a small toilet right over the tank for now and make "direct deposits".


It sounfs to me that a toilet connected to the septic is what your septic excavator recommended. That will need some water for flushing. Otherwise a typical outhouse onthe hatch will result ina pyramid of excrement building up. I don't see a problem with a toilet as eventually treated water will exit bythe pipes and leach field. But that does need water along with the excrement. An outhouse will not supply the liquids, unless as mentioned rain gets in and you do NOT want that.

I think you need to haul in water in sugficient quantity to allow flushing or use porta potties. Maybe it is time to get the well drilled? That is often done before building and IMO is a good idea. Septic first, well second, along with electric grid connection if any. Then build the cabin.

I assume the road or driveway is in already as that is needed for equipment access and supplies. That should be wide enoughand done well enough for delivery trucks, propane and septic pumping as well asemergency vehicles and have a turnaround. Zoning often has minimums.

jhp
Member
# Posted: 11 Aug 2020 17:45
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Something you could do if you don't have a well yet is capture rainwater off the roof of the outhouse. Just checked a calculator and a 4x8 roof will net about 20 gallons in a 1 inch rainfall.

So if you built a nice oversized outhouse, say 6x8 and captured rain off of both sides of the roof you'd be able to fill a rain barrel with pretty much any good rainstorm.

Figure you can hold maybe 45 gallons of water in a 55 gallon barrel (you lose a few gallons at the top and bottom of the barrel for inlet and outlet), 1.6 gallons per flush that's about 28 flushes per storm.

If you mount the rain barrel above the toilet height-wise, you just have to open a valve to refill it, though it will take a bit of time.

If you want to get really fancy, grab a small solar panel and charge controller, a small AGM battery, and small 12v water pump and make the whole process super simple. Probably cost around $200 for the whole kit, except the building and gutters.

old243
Member
# Posted: 11 Aug 2020 21:08
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I think an out house over a septic tank would work well. It really is no different than a pit except larger. You should fill the tank with water, as well . At our place if you left a septic tank empty , it would float out of the ground much like a boat I think your contactor gave you good advice. We have a high water table, old 243

Shadyacres
Member
# Posted: 11 Aug 2020 21:37
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I have a 1000 gallon concrete tank at the cabin i just bought beside us. I was thinking of maybe building an outhouse and use that . It would have to be pumped out though. I don't know how long it would take to fill up. We also have a well and power at that location. Only about 400 feet from our cabin. I didn't want anyone else to buy it and be so close.

Sylvan
Member
# Posted: 14 Aug 2020 17:34
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Thanks everyone. Appreciate all the input. I'll keep you posted how it turns out. I am leaning towards putting the covered outhouse over the hole so no rain getting in. Setting up a rain barrel as jhp suggested and using that to keep water in the tank. Still not sure about odor. Guess I'll just have to see.

toyota_mdt_tech
Member
# Posted: 14 Aug 2020 19:07
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It needs to enter the septic tank via the inlet, not the manhole cover. Septic systems develops a crust at the top and sludge at the bottom, the incoming goes between these. Using the manhole cover would not let this happen. Also, no air entering tank. With open manhole, it would.

Can you hook up a holding tank into outhouse, and after its filled up, dump it via a pipe hooked to inlet with a gate valve etc like an RV?

Aklogcabin
Member
# Posted: 15 Aug 2020 09:30
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I like this . Good ol figure it out . Using what you have. The government doesn’t have the perfect answer. I think jhp had a great idea. Maybe missing something. But if you had a vent pipe coming from the other manhole . Like a regular cleanout. But extended above the outhouse for odor. If there is water in the pee trap it will stop odors. It is an outhouse. And old 243 always has good ideas ( thanks ) .

ratfink56
Member
# Posted: 17 Aug 2020 19:37
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I did this for a bit years back. It can be splashy.

NorthRick
Member
# Posted: 18 Aug 2020 18:08 - Edited by: NorthRick
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Quoting: jhp
Something you could do if you don't have a well yet is capture rainwater off the roof of the outhouse. Just checked a calculator and a 4x8 roof will net about 20 gallons in a 1 inch rainfall.

So if you built a nice oversized outhouse, say 6x8 and captured rain off of both sides of the roof you'd be able to fill a rain barrel with pretty much any good rainstorm.

Figure you can hold maybe 45 gallons of water in a 55 gallon barrel (you lose a few gallons at the top and bottom of the barrel for inlet and outlet), 1.6 gallons per flush that's about 28 flushes per storm.

If you mount the rain barrel above the toilet height-wise, you just have to open a valve to refill it, though it will take a bit of time.

If you want to get really fancy, grab a small solar panel and charge controller, a small AGM battery, and small 12v water pump and make the whole process super simple. Probably cost around $200 for the whole kit, except the building and gutters.



While I think all that would work, building a regular outhouse would be easier especially if you have your excavator dig the hole while he is on-site.

You didn't mention how long you expect to use this setup.

ryan99
Member
# Posted: 29 Apr 2021 14:09
Reply 


Hi all, thanks for great info.
Any follow up from this Sylvan? Did you get something done?
I am looking to do something similar but with an rv toilet. I am going to build a small camp washroom with rainwater collection to run the rv flush toilet and a shower. I am planning on running the toilet into the inlet of a yet to be determined septic tank and the shower and sink into a couple of infiltrator sections. I know that the rv toilets are intended to be right above a holding tank but I have read that you can do a pipe run of up to 15 feet with them. I will make sure to install a clean out but it seems it should work well and not fill up the tank too fast. Has anyone done that?

darz5150
Member
# Posted: 29 Apr 2021 16:03 - Edited by: darz5150
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Yep. We use a thetford rv toilet, into standard pvc pipe. Uses very little water. We do not flush any tp.

gsreimers
Member
# Posted: 29 Apr 2021 18:46
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We have a 1000 gallon septic tank and drain field. What you are contemplating is exactly what we did for 5 years until the cabin had indoor plumbing. Pumped quite a bit of water in it 2 or 3 times a season. We now have indoor plumbing. The tank has been in for 7 years and there is no sediment and no real scum layer. It seems to do it's job and digest everything just fine.

gcrank1
Member
# Posted: 29 Apr 2021 23:00
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Ive had my own old, and healthy/ie, it works fine, septic system at home for 35ish years. Granted it is mostly just the two of us.
Imo the full of water tank proper wont care if the stuff comes in the side inlet or the top, the scum layer will ooze right over 'a drop', the bacteria will work and the sediment will sink. The 'overflow' of grey water will go out the outlet to the drain field. You may want to dump in a 5 gal. pail of rain-barrel water after every weekend.
You could set up a T fitting on the inlet pipe to use as a riser to the toilet rather than setting it on the inspection port, then the piping would feed the tank as intended and later, when you do 'proper plumbing' you could just cap that T off.

ryan99
Member
# Posted: 30 Apr 2021 02:15
Reply 


Thanks all,

darz5150, Are you just using your tank as holding or do you have a drain field? How often do you have to pump it out? Are you using the rv toilet in your cabin or an outhouse?

I plan on keeping the extra outhouse washroom with rv toilet once the cabin is done. Hopefully that way the kids won't track so much into our new 16x24. It should be great for any camp visitors we get too!

I am wondering though if the rv toilet is easier to winterize as well. Does anyone use one in their cabin?

Cheers

Brettny
Member
# Posted: 30 Apr 2021 06:06
Reply 


If you ever plan on having the tank pumped you cant use it like an outhouse. It will need water to keep from being a shit brick when it's time to pump it out.

My brother bough a RV in AZ that they left the black tank with stuff in it. He had to put ice in it and drive around rough roads to break up the brick.

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