Fresh/Gray Tanks

o1marc · 05-02-2019, 01:16 PM

I bought 3 tanks, the seller made a point of telling me they only had fresh and not gray. I now see a concern with the fresh tank. It has only one larger fill hole and 3 1/2" "drain" holes. On the gray I would need 2 larger holes for fill and drain. Anyone have a fix for this issue that doesn't require replacing a tank.

Ninjakitty · 05-02-2019, 01:21 PM

Cut a hole where you want it to feed, tap some threads in in it or some 3M 5200 to a piece of pipe

family wagon · 05-02-2019, 01:28 PM

So, if I understand correctly, you have a tank designed for fresh water but want to use it to carry gray water.

Well... you could fix the problem at the source by using a screen to prevent large particles getting into the tank. Something like a sediment filter used in irrigation systems, maybe?

Those water tanks are usually made of polyethylene. I'm not sure there are any adhesives that really bond well with PE; that's why the fittings are usually spin-welded in place. A spin welder is basically a router (yes, a wood router) with a jaw for holding the fitting. You might be able to find a shop nearby which has a spin welder.. but I wouldn't hold my breath.

How about a bulkhead fitting? I arbitrarily clicked on Amazon at a 2" bulkhead fitting for US$8 and a 3" bulkhead fitting for US$31.

o1marc · 05-02-2019, 02:07 PM

Quote:

Originally Posted by family wagon

So, if I understand correctly, you have a tank designed for fresh water but want to use it to carry gray water.

Well... you could fix the problem at the source by using a screen to prevent large particles getting into the tank. Something like a sediment filter used in irrigation systems, maybe?

Those water tanks are usually made of polyethylene. I'm not sure there are any adhesives that really bond well with PE; that's why the fittings are usually spin-welded in place. A spin welder is basically a router (yes, a wood router) with a jaw for holding the fitting. You might be able to find a shop nearby which has a spin welder.. but I wouldn't hold my breath.

How about a bulkhead fitting? I arbitrarily clicked on Amazon at a 2" bulkhead fitting for US$8 and a 3" bulkhead fitting for US$31.

Can you tell me how you would get the big nut through the 2" hole"?

family wagon · 05-02-2019, 03:10 PM

Quote:

Originally Posted by o1marc

Can you tell me how you would get the big nut through the 2" hole"?

OK, I was so busy being a smart aleck with the strainer suggestion that I didn't think through how to get a bulkhead nut into the tank very well (at all).

But now that you've called me out on that..

Waste tanks often use a rubber grommet for the inlet fitting. The drain pipe presses directly into the grommet, ie there's no threaded connection. If the bulkhead fitting is needed only for the outlet, what about choosing a grommet for the inlet that fits a hole that's big enough to pass that inner nut through? Maybe that'll require a larger pipe than you want/need for the drain leading to the tank, but it could be sized down with a bushing or a reducer.

o1marc · 05-02-2019, 03:19 PM

Quote:

Originally Posted by family wagon

OK, I was so busy being a smart aleck with the strainer suggestion that I didn't think through how to get a bulkhead nut into the tank very well (at all).

But now that you've called me out on that..

Waste tanks often use a rubber grommet for the inlet fitting. The drain pipe presses directly into the grommet, ie there's no threaded connection. If the bulkhead fitting is needed only for the outlet, what about choosing a grommet for the inlet that fits a hole that's big enough to pass that inner nut through? Maybe that'll require a larger pipe than you want/need for the drain leading to the tank, but it could be sized down with a bushing or a reducer.

With the water tank gravity fed with no pressure, I would have no problem tapping a hole in the top (side) of the tank and threading in a fitting for a 3/4" hose. I purposely got a gravity feed receptacle for the outside and not a screw on hose fitting that can pressurize and burst the tank if you don't pay attention. Always have a relief valve on the tank.

MambaJack · 05-02-2019, 03:22 PM

I have used something called a Uniseal found on ebay for my aquaponic system tapping into 55 gallon plastic barrels and ibc totes. works great.

I will probably do the same for my grey tank.

Drill appropriate hole, place seal, then push in pvc.

family wagon · 05-02-2019, 03:33 PM

Quote:

Originally Posted by o1marc

With the water tank gravity fed with no pressure, I would have no problem tapping a hole in the top (side) of the tank and threading in a fitting for a 3/4" hose. I purposely got a gravity feed receptacle for the outside and not a screw on hose fitting that can pressurize and burst the tank if you don't pay attention. Always have a relief valve on the tank.

Yeah, there are several ways to crack that nut. For my own fresh tank I didn't want to have the traditional filler neck; I preferred to fill it by opening a valve while the pressurized "city water" is connected. An air vent is needed in any case. The regular filler neck in your approach provides that; for mine I have an extra threaded port at the top of the tank to serve as both vent and overflow.

But I thought we were talking about how to make one of your fresh tanks serve for gray holding. Maybe what you were getting at is that the gravity feed receptacle will be re-purposed as the inlet on the tank that gets used for the gray water? In that case, if there's no larger hole yet to be cut in the tank, maybe the bulkhead fitting won't work out.

o1marc · 05-02-2019, 03:35 PM

Quote:

Originally Posted by MambaJack

I have used something called a Uniseal found on ebay for my aquaponic system tapping into 55 gallon plastic barrels and ibc totes. works great.

I will probably do the same for my grey tank.

Drill appropriate hole, place seal, then push in pvc.

That looks like a decent option.

o1marc · 05-02-2019, 03:43 PM

Quote:

Originally Posted by family wagon

Yeah, there are several ways to crack that nut. For my own fresh tank I didn't want to have the traditional filler neck; I preferred to fill it by opening a valve while the pressurized "city water" is connected. An air vent is needed in any case. The regular filler neck in your approach provides that; for mine I have an extra threaded port at the top of the tank to serve as both vent and overflow.

But I thought we were talking about how to make one of your fresh tanks serve for gray holding. Maybe what you were getting at is that the gravity feed receptacle will be re-purposed as the inlet on the tank that gets used for the gray water? In that case, if there's no larger hole yet to be cut in the tank, maybe the bulkhead fitting won't work out.

If you look at my tank pictured below, you will see 3 small access holes and one large hole. I assumed the large hole would be my drain and that I would need something larger for a drain into the tank. A bulkhead fitting only works when you can access both sides. I will use one for the smaller access ports for a breather overflow. I keep getting water supply into this tank on my mind, but it's a waste tank, not a fresh fill tank. So I need one bushing the size of the drain pipe going into the tank, probably 1-1/4" which I will step down from the 1-1/2" Hepvo trap. I think I'm good now. Thanks for input everyone.

I don't know why I keep talking about my fill valve and vent/ overflow, those go to fresh not to gray you dumb arse.

ol trunt · 05-02-2019, 07:28 PM

The fresh tanks work fine for grey as well. All my tanks were used so nearly all the openings were in the wrong place.I was able to get spin weld fittings nearby so I set about rigging up my own spin tool--the router thingy. A word of caution. a router turns at about 25,000 rpm's and when the replacement plug or new fitting touch the tank, both touching surfaces become molten and until you get the hang of spin welding its easy to get a bath of blistering hot plastic--I sure did!

.

This is my 40 gallon grey tank with various home done spin weld fittings.

.

Jack

Sleddgracer · 05-02-2019, 07:41 PM

https://www.youtube.com/watch?v=fMdLWAYr7Ck

ol trunt · 05-02-2019, 07:55 PM

Great video though I like most "real men" wouldn't have watched it had I even known about it.

Jack

PNW_Steve · 05-06-2019, 11:02 AM

Spinweld is the way to go.

I have used lots of Uniseals and they are cool but I have had some issues with them leaking just a little bit and with larger (2"+) seals causing the tank to crack.

Doktari · 05-12-2019, 04:21 PM

This is great. I’ve been wondering about how to modify fittings on my tanks. Good to learn about uniseal and spin welding. I’ve been wondering about plastic welding. Has anyone tried it?? Last time I did anything remotely similar was dripping molten plastic on the scratches of my skis almost 40 years ago. Oh, and heating and bending plastic conduit.

Yukon Cornelius · 05-13-2019, 07:50 AM

Quote:

Originally Posted by Doktari

This is great. I’ve been wondering about how to modify fittings on my tanks. Good to learn about uniseal and spin welding. I’ve been wondering about plastic welding. Has anyone tried it?? Last time I did anything remotely similar was dripping molten plastic on the scratches of my skis almost 40 years ago. Oh, and heating and bending plastic conduit.

Plastic welding is kind of like soldering, and there is a ton of options for various kits. My experience is mostly with the airless systems. And I have found that the speed welding tip makes the smoothest and most consistent welds, at least for me anyways. They are fairly common amongst rednecks, as we don't like paying the price for new plastics...and we tend to beat them up on our sleds, quads, bikes, etc. If coupled with a decent heat gun your options for dealing with plastics are virtually limitless.

this one if similar to the one we have up here....however we did not pay that price......
https://www.amazon.ca/Urethane-Suppl...gateway&sr=8-5

ThemadTurk · 05-13-2019, 10:43 AM

i used uniseal gadgets on mine. very tight and very good seals

alpine44 · 05-14-2019, 08:31 AM

Another option is to put an oval hand hole in the top surface of the tank. That allows any regular flanged fitting to be installed.

The lid to close the hand hole is made from two pieces of PE marine lumber (like Starboard) that are clamped together with crews. The inner piece will fit through the oval hole when turned 90 degrees. The flanges are sealed with a bead of RTV that is cured with the lid only slightly tightened. Final tightening of the screws compresses the 'gasket' and seals the whole deal.

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