Gray water fittings and connections?

[Roy in TO]

I'm considering using a second Polyrama ERT 8.25 to my 13' Boler American to use as a gray water tank. I'm planning on putting it between the frame rails under the dinette. It should be a pretty simple set up to use with only a sink. Like in the diagram:





I'm thinking of using the pre-existing freshwater filler tube on the curbside for the vent and washout. That takes a 1" hose. Does it need a check valve because the sink is higher than the inlet?

Do you think I could use a garden hose from the Y valve from the sink to the tank? The sink originally empties through a garden hose to the outside. If so, what size fitting would be best ... 5/8" or 3/4" or ????

Can I get away with a 1" drain to the Ball valve for dumping or should I upsize to 1.5"?

If you have a gray tank on yours, what size hoses and fittings or connections do you have on your trailers. I know the bigger setups use the 1.5" or 2" Black PVC like in houses, but what do us little guys use?

[Harry Young]

Wow, good Question!

Emptying greywater to the outside is one thing, when you connect to a tank there are some pre-cautions to consider...One and foremost is safety, the tank is a breeding ground for some very very nasty bacteria, any system must address the rules of good health regarding the issues of the natural world. Nature is un-yielding and can ruin a trip...Bacteria will multiply in any tank and will migrate backwards up any direct connection of any direct line to the galley sink. A p-trap incorporating an air gap to the bottom of the sink strainer is essential.

Black water and grey water systems use acknowledged tricks learned over time to limit risks. The trap under the sink is one, proper venting outside another, proper placement of the inlet to the waste tank are important. Look closely at current systems being built and copy them, they must follow current standards of prevailing proven wisdom.

Sizes are generally sewer and 1 1/2 and 1 1/4...as of late some R.V. sizes are becoming unique to R.V. manufacturers...Be aware that common garden hoses contain high lead contents "why they are flexable" so using them for water supply is a no no...Black A.B.S. plastic pipe is poison...N.F.S. is safe that logo is on C.P.V.C...as it is on vinyl hose for R.V.s.

Your question is a real good one. Its good you want to give some thought to this project, Generally people are not aware of these issues.

I would be happy to send pics of trailers... but an R.V. supply would be very helpful or cruising new trailers to learn.

Sincerely
Harry

[Pete Dumbleton]

I wouldn't use the fresh vent for the gray. Aside from the gases mixing, sloshing on the road might cause fluid mixing, either of which may cause gastroentrological mixing in the humans...

[Frederick L. Simson]

I'm considering using a [b]second Polyrama ERT 8.25 to my 13' Boler American to use as a gray water tank.

I'm thinking of using the pre-existing [b]freshwater filler tube on the curbside for the vent and washout.

And what are you planning to use to fill the freshwater tank? Your statement infers that you will have 2 tanks: 1 freshwater (supply) and 1 gray water (holding).

I believe that most holding tank vents exit the trailer thru the roof to place it 1: above any water inlet and 2: as far away from your nose as possible. While gray water isn't quite as smelly as black water, it is still smelly.

[Roy in TO]

As Ricky Ricardo would say, I've got some 'splainin to do....

Nature is un-yielding and can ruin a trip...Bacteria will multiply in any tank and will migrate backwards up any direct connection of any direct line to the galley sink. A p-trap incorporating an air gap to the bottom of the sink strainer is essential.

Thank you Harry,

I understand exactly what you are saying. I'm in Health care and put myself through school doing home renovations. I never really thought about the difference between draining to the outside and using a tank though. Good point!

I'll have to do some research on what's available for gray tanks to keep things under control biologically. I don't imagine we will use it that often, but I am trying to set everything up for boondocking.

The curved line from the sink was my attempt at trying to represent a trap. I have not been to the plumbing section in a while looking at the new stuff, but I understand many of the new homes use a lot of the newer plastic lines. I'll have to see what is on the market to use.

I wouldn't use the fresh vent for the gray. Aside from the gases mixing, sloshing on the road might cause fluid mixing, either of which may cause gastroentrological mixing in the humans...

Good points Pete! I think you misunderstood what I was doing, I'll try to 'splain what I had planned a little futher down.

And what are you planning to use to fill the freshwater tank?
I believe that most holding tank vents exit the trailer thru the roof to place it 1: above any water inlet and 2: as far away from your nose as possible.

I am planning on removing both the electrical inlet and city water fill on the street side of the trailer.





Replacing them with one of these lockable city water and fresh water fill units with the vent for the fresh water tank built in. I could then move the electrical inlet to just above the name plates.





That would leave the old curbside tank fill inlet not connected to anything.





The Polyrama ERT 8.25 are 4" high and the frame height is 3" so I am going to have to weld something on to hold the tanks in place. My thoughts were to run 4 peices of angle iron from side to side, 2 for each tank. If I hinged the curbside ends, I could use pins and chains on the streetside ends to allow for the tanks to be lowered on one side to drain completely. At 12 lbs empty they should be easy enough to lift back up.

That's where my idea of using the old tank fill opening on the curbside comes to play. That used to lead into a tank under the bench, but could be quite nicely used to flush out the gray tank. Making for good water flow when the tank was being drained from the other side.

Doing that presents 2 problems. The old fill (new flush) is below the level of the sink. If we over fill the gray tank, it will flow out the new flush. I could use a stopper in it but then I'd lose my vent. That would mean, I'd have to run a vent line on the inside to the top of the sink and back down through the floor like Scamp does. (or so I understand).

Or I could put a single holed stopper in the old fill (gray flush) with a small hose that runs through it and run it up the outside clipping it onto the window frame on those occassions where we might use the gray tank. That would give me a visible indicator if we over fill the tank. I could even use one of those wine makers valves at the end of the hose that only lets gasses out.





Has all this 'splainin made any sense of what I'm considering yet?
Any questions?
Any suggestions?