Additional Grey Tank Capacity when Boondocking

PeteB · 05-14-2008, 02:22 AM

My tank set up has the grey and black tank drains joining at a "Y" just before the connection point for the sewer hose. Each tank has a shut off valve so in order to gain more grey tank capacity when Boondocking I have done the following:

I installed an additional knife vale at the hose connection point which, when closed, will allow me to open the two tank valves to allow the grey tank to equalize volume into the black tank as the grey tank always fills up more quickly than the black tank. I can them shut off the valves if I feel it necessary.

The additional knife valve has the proper connector lugs so the hose can still be hooked up to drain. Does anyone see any downside to this arrangement?

Thanks, Pete

PeteB · 05-14-2008, 02:22 AM

My tank set up has the grey and black tank drains joining at a "Y" just before the connection point for the sewer hose. Each tank has a shut off valve so in order to gain more grey tank capacity when Boondocking I have done the following:

I installed an additional knife vale at the hose connection point which, when closed, will allow me to open the two tank valves to allow the grey tank to equalize volume into the black tank as the grey tank always fills up more quickly than the black tank. I can them shut off the valves if I feel it necessary.

The additional knife valve has the proper connector lugs so the hose can still be hooked up to drain. Does anyone see any downside to this arrangement?

Thanks, Pete

Harry B · 05-14-2008, 08:03 AM

I have been using this arrangement when I need additional gray water storage for a while and works just fine

John_Canfield · 05-14-2008, 08:36 AM

I use a small 110V "little Giant" pump to pump from the gray to the black. I use a Valterra garden hose adapter for the drain (connected to the suction side of the pump) and the output pumps into the flush hose fitting on the black tank. This works really well (so far.)

Easyrider · 05-14-2008, 03:40 PM

I've used the additional knife valve trick for a few years now and recommend it to everyone. Some people get alarmed

when they hear what I've done and think I will get black water gunk into my grey water tank!

So what? It all goes down the same drain and it's no different than a house and septic tank. I think the only reason we have separate holding tanks in the first place is so you can be hooked up to a full service site and take unlimited showers if you desire and not have to worry about the black water stuff piling up and not draining out properly. I think if you go back far enough in rv history you will find that rv's originally only had one holding tank back when full service campgrounds didn't exist with full hookups. All your fixtures that drain into your grey water tank have P-traps in the drain to prevent any odors from coming back up. It's no different than in your house.

SteveG · 05-14-2008, 05:20 PM

I am thinking until you have caught the cold water from the shower in a bucket and the cold water from the sink faucet in a large bowl before shaving so you can pour this unused water into the black tank via the toilet bowl, you can't really appreciate the transfer valve to shift gray water to the black tank.

I am thinking I need to retire the bucket and bowl. Thanks for the idea.

Carnles · 05-14-2008, 05:33 PM

SteveG that is hilarious!!!!!!!!

It doesn sound like a great idea.

theroc · 05-14-2008, 05:51 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by John_Canfield:
I use a small 110V "little Giant" pump to pump from the gray to the black. I use a Valterra garden hose adapter for the drain (connected to the suction side of the pump) and the output pumps into the flush hose fitting on the black tank. This works really well (so far.) </div></BLOCKQUOTE>

Can you tell us what "Little Giant" pump you're using and a little bit more about how you've set it up? Thanks, John.

Jackm · 05-14-2008, 07:43 PM

We've used the black tank to store gray water but the best solution for us involved the use of a 35 gallon saddle tank that sat on a hitch-mounted cargo carrier. The cargo carrier could be mounted on the RV or the tow vehicle. They sell them at most RV supply stores. Thirty-five gallons weighs approximately 300 pounds so be sure to get the cargo carriers that have a 500 pound capacity. They sell carriers that fold up out of the way if this is a feature that matters.

The polyethelene saddle tank, available on the Internet, was secured to the cargo carrier with bungee cords. The tank costs around $60. I installed a ball valve on the tank to simplify dumping. The best thing about this arangement was the flexibility. I could use the tank to either haul away gray water or to provide an additional 35 gallons of on-site capacity.

Jack

PeteB · 05-15-2008, 01:53 AM

Thanks for all your replies. I am looking forwsrd to trying out the new arrangement as it should greatly extend my capacities.

Pete

SteveG · 05-15-2008, 03:11 PM

John, to prepare for bucket freedom I have done some research. Is this the pump? See specifications below photo. It has a stainless steel housing etc. for about $95. Also found a not stainless steel pump manufactured by Wayne at Home Depot for about $75.

Following that is a photo of the Valterra termination cap with garden hose fitting to attach to the gray tank dump outlet As you do, I already have a black tank flush hose connection. Now I just need to go to the store! Thanks

Pony Pump Water Transfer Pump
This lightweight, self-priming, portable pump with stainless steel pump head can be used to empty waterbeds, drain water heaters or aquariums, pump out a basement, transfer water to an RV, pump boat bilges, pump out stock tanks, and in other applications where water needs to be transferred. Intermittent duty is 15 minutes "ON" and 45 minutes "OFF".
"¢ 115 Volts, 6' Power Cord
"¢ Operates in-line only
"¢ Intermittent liquid temperature to 120 degrees F.
"¢ Maximum flow rate is 360 GPH @ 1' of head
"¢ Intake & Discharge - 3/4" Male Garden Hose Thread / 3/8" FNPT
"¢ Stainless Steel Volute, Housing, Cam, and Motor Shaft
"¢ Buna-N Impeller and Shaft Seal
"¢ Two extra impellers and gaskets included
"¢ General water transfer
"¢ Drain water beds
"¢ Drain water heaters

Model Number: PP-1S

Below is the Wayne non stainless steel sold by Home Depot for about $75

Below is the Valterra termination cap with garden hose fitting sold at Camping World.

Chief · 05-16-2008, 04:33 AM

Steve, same setup that I use and it sounds as if John is using same. Works for us.

theroc · 05-16-2008, 05:32 AM

Thanks, Steve! So I can just go to Home Depot to buy the pump?

I'd rather use that set up John and Chief use rather than use the extra knife valve as Pete is going to use.

Easyrider · 05-16-2008, 03:49 PM

Keep in mind the extra knife valve costs less than $20.00 and requires no wiring or power to accomplish the same thing John's does at greater expense.

theroc · 05-16-2008, 04:44 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Easyrider:
Keep in mind the extra knife valve costs less than $20.00 and requires no wiring or power to accomplish the same thing John's does at greater expense.

</div></BLOCKQUOTE>

Good point, Steve. However, despite what you said about no big deal about having black water in the gray tank, for some strange reason, I'm uncomfortable doing that.

Plus, I use a standard discharge hose. I like being able to rinse the hose out with gray water after emptying the black tank. If both tanks contained black water, wouldn't the hose stink more because there's no soapy rinse flushing it out?

Harry B · 05-16-2008, 06:23 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I like being able to rinse the hose out with gray water after emptying the black tank. If both tanks contained black water, wouldn't the hose stink more because there's no soapy rinse flushing it out? </div></BLOCKQUOTE>

As I stated earlier in my earlier post, I also use the additional 3rd valve method and at least on my coach black water does not enter the gray water tank.

On my Horizon the gray and black tanks reside next to each other. Upon installing the 3rd valve and closing it, I open the gray water tank valve first. Then I open the black water tank valve. Now the gray water flows from the gray tank to the black tank as the gray water tank is fuller than the black water tank. You can hear the water shuttle from the gray to the black tank. It takes maybe 30 seconds or so to complete. When I no longer hear the water shuttle, I close both the gray water and black water tank valves and leave the 3rd valve closed and attached until I am ready to dump or perhaps repeat the above procedure again.

I don't leave the valves open for water in the tanks to mix while I continue to use the facilities of the coach.

When I get ready to dump, I attach the hose to the 3rd valve and open only the 3rd valve to clear out what is in the pipe between the gray black and 3rd valve . Then I open the black valve and dump as you would normally do. Next close the black valve and open the gray water tank valve. In the process of draining the gray water tank it rinses the hose and the 3rd valve clean.

So the process is much the same as without the 3rd valve attached. I only open the gray and black valve together to allow the water to shuttle and then I close them both again. This eliminates waste water flowing from the black tank to the gray water tank.

theroc · 05-16-2008, 06:55 PM

Oh, thanks for the explanation, Harry.

I didn't recall you saying that your black water isn't entering the gray tank.

But what happens when the tanks get close to each other in capacity ...won't you then have black water entering the gray tank; or am I visualizing wrong?

edit: ok, I didn't realize you close the valves after the procedure is over. Nevermind

Harry B · 05-16-2008, 07:31 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I didn't recall you saying that your black water isn't entering the gray tank. </div></BLOCKQUOTE>
'rocco

You are right in that I did not mention in my initial post, that in my opinion no black water is entering the gray water tank.

You can clearly hear when the shuttling of water from the gray to the black tank is completed. So the key issue is to close both valves again upon completion of the process. This should prevent the black tank's content from entering the gray tank.

Easyrider · 05-16-2008, 07:38 PM

I use the same method as Harry, it's a great way to rinse out the black water tank. Fear of getting any black water into the grey tank is still all in the mind in my opinion. Have you ever smelled your grey water? It's just as bad as the black. Neither grey or black is supposed to come back up your drains into your sinks or showers. The "P" traps in your drains prevent odor from coming up into your sinks and showers. The black water will not hurt your grey water tanks, they're made of the same materials. Go down into the basement of your house, all the drains from your living area, from your sinks, showers, AND toilets connect to the same sewer pipe! Your RV is no different! The only reason you have a separate black water waste tank is so you can accumulate enough water before draining it to flush the solids out of it. You couldn't do that if you had only one waste holding tank and were hooked up to a sewer campsite and wanted to leave your drain valve open to be able to take unlimited showers, do laundry, and wash dishes alot. Having separate holding tanks allows you to do that! You have two holding tanks for convenience- not for safety! For those who want to pump the grey water into the black, I say go ahead, it's a neat accessory, but the extra valve only took about 5 seconds to put on. I leave mine on permanently, and like Harry said only takes about 30 seconds to equalize. It's very simple and easy to use, and cost is less than $20.00. Use whatever you are most comfortable with, but the big thing is either way allows you more time between dumping, I just wonder why they build RVs with the same size black and grey water tanks for the most part, everyone I've ever talked to about it says their grey water tank fills up much sooner than the black water tank. Manufacturers- are you listening?

Harry B · 05-16-2008, 08:09 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I just wonder why they build RVs with the same size black and grey water tanks for the most part, everyone I've ever talked to about it says their grey water tank fills up much sooner than the black water tank. </div></BLOCKQUOTE>
Steve,

There are other manufacturers that have figured this out and do make gray holding tanks that are larger than the black water tanks. It is just that Winnebago has not done so yet as far as I know.

The good thing is that the combined capacity of my black and gray tanks equals the capacity of the Fresh water tank. So when the Fresh water tank is empty I know it definitly time to dump.