Easy way to repurpose an unused black tank for grey water

[NCeagle]

Here's one way to use a black tank that may be available for other uses (e.g., a composting toilet installed).  Since the black and grey tanks share the same drainage pipe, an unused black tank is only good for holding extra grey water without major modifications to the plumbing.  It's pretty simple to put a cap with a hose connection on the end of the tank drain pipe and then use an inline hose pump to pump up to 15 gallons (in my case) of grey water into the black tank.

I never thought having extra grey water capacity would be important, but camping on the East coast involves pretty hefty fines if you are caught draining your gray water into nature.  I also assumed that camping with full water / electricity hookups meant unlimited, long hot showers in the Ollie (not the case!).  So, 15 extra gallons of grey water capacity could mean you don't have to tow your trailer over to the dump station in the middle of your camping trip because you have to empty your grey water tank.

Edited March 22, 2021 by NCeagle
spelling

[jordanv]

On 3/22/2021 at 4:35 AM, NCeagle said:

Since the black and grey tanks share the same drainage pipe, an unused black tank is only good for holding extra grey water without major modifications to the plumbing.  It's pretty simple to put a cap with a hose connection on the end of the tank drain pipe and then use an inline hose pump to pump up to 15 gallons (in my case) of grey water into the black tank.

How did you do this, seeing as there is only one outlet for the grey and black tanks. 

[SeaDawg]

Jordanv, did you get the composting toilet?

[jordanv]

4 minutes ago, SeaDawg said:

Jordanv, did you get the composting toilet?

Yes, we did. We are thoroughly enjoying it as well. We are on the borderline of boondocking currently (we have power and water but no sewer hookup) and we are glad we do not have to go into town to dump a black tank. Our host lets us drain the grey water into the ditch 👍

Edited March 23, 2021 by jordanv

[SeaDawg]

Then , you don't even need to worry about his process .

I'm interested in more detail, as well.

 

[JRK]

Me too. I have a full grey water tank right now, almost, and am boondocking on BlM land. Not supposed to drain anything onto dirt. 

What becomes the inlet for the black water tank? Draining the grey water, and using a pump into the black water tank I understand, except what becomes the black water tank inlet, if the grey water tank is emptying?

[John E Davies]

Transfer the grey water through a portable pump (with a good inlet filter) into the black tank rinse port (on the left side in front of the tires.)

A simple  solution indeed, except for keeping hair and food debris from clogging the filter. That could get tiresome....we need pictures please.

There is also the problem of venting, the tank connects to the 1.5” black vent pipe that goes out the roof, it tees into it under the sink. If the black tank should get too full, the water will flow into the sink, and then onto the floor, and back into the grey tank via the drain. Hopefully the blade valve is open! What a computer geek would call a waste water Infinite Loop . 😀 That could be very entertaining. Maybe it’s time to revive this thread... https://olivertraveltrailers.com/forums/topic/3213-grey-water-recycling/. It really is a shame that the black tank is several inches higher than the grey one, if they were level you could gravity feed one into the other quite easily.

John Davies

Spokane WA

Edited March 23, 2021 by John E Davies

[ScubaRx]

A "relatively" simple solution would be to drain the bathroom sink water into the black tank. You could achieve this with gravity only. Pull the black tank valve to dump at any time. I would save 15 gallons of space in the gray tank.

[SeaDawg]

38 minutes ago, ScubaRx said:

A "relatively" simple solution would be to drain the bathroom sink water into the black tank. You could achieve this with gravity only. Pull the black tank valve to dump at any time. I would save 15 gallons of space in the gray tank.

I've  mentioned this several times, but definitely the "easiest " I  can think of. 

Many SoB trailers drain bath sink to the black. Relatively easy plumbing retro in an Ollie. 

 

 

[NCeagle]

10 hours ago, John E Davies said:

Transfer the grey water through a portable pump (with a good inlet filter) into the black tank rinse port (on the left side in front of the tires.)

A simple  solution indeed, except for keeping hair and food debris from clogging the filter. That could get tiresome....we need pictures please.

There is also the problem of venting, the tank connects to the 1.5” black vent pipe that goes out the roof, it tees into it under the sink. If the black tank should get too full, the water will flow into the sink, and then onto the floor, and back into the grey tank via the drain. Hopefully the blade valve is open! What a computer geek would call a waste water Infinite Loop . 😀 That could be very entertaining. Maybe it’s time to revive this thread... https://olivertraveltrailers.com/forums/topic/3213-grey-water-recycling/. It really is a shame that the black tank is several inches higher than the grey one, if they were level you could gravity feed one into the other quite easily.

John Davies

Spokane WA

@John E Daviesis right on.  His description is how I did it.  I did NOT use a filter since we don't put any food / grease into our grey tank so it's soap and hair only - not a problem for the pump (as of yet).

I'm not sure what good pictures would do - I didn't take any - but it would show a hose coming out of the back bumper (connected to the black / grey drain pipe with this: Camco Durable Sewer Cap with Hose Connection- Caps the Sewer Connection to Prevent Leaks, Easy Install and Simple Use (39463)).  Then there's a pump like this Trupow 1/10HP 330GPH 115-Volt Mini Portable Electric Utility Sump Transfer Water Pump with Water Hose Kit that attaches to the drain hose and subsequently another hose to the black water flush port / inlet.  Hook it up, then pump in some grey water until the black tank is full.  Common sense provides the valve configurations...  when filling the black tank, the black tank valve must be closed and the grey must be open.

Problems can be avoided with the vent, etc. by not overfilling the black tank.  It's not that hard to be careful.  I timed how long it took my pump to transfer 15 gallons of grey water to a bucket before I tried this.  It took that pump listed above 3 minutes and 45 seconds for 15 gallons.  I ran the pump for 3 minutes and 30 seconds and then checked my black tank SeeLevel monitor and it was at 95%.  I figured that's close enough, so I can run the pump for 3.5 minutes safely.

There's no other way I can think of to easily use the black tank without plumbing modifications.  I wanted to preserve everything for resale just in case. 

It's also worth noting that we ordered the composting toilet with our Ollie, so the black tank is there but has NO hole in the top cut out.  If you upgraded to the composting toilet and you still have the hole on top of the black tank you would have to cover / seal the hole.

Edited March 24, 2021 by NCeagle

[John E Davies]

That pump looks interesting, can you buy replacement impellers and gaskets? It doesn’t have a switch, maybe adding a waterproof one would make it safer. Does it come with silicone grease? BTW we really like to look at pictures😀

Thanks.

John Davies

Spokane WA

[NCeagle]

2 hours ago, John E Davies said:

That pump looks interesting, can you buy replacement impellers and gaskets? It doesn’t have a switch, maybe adding a waterproof one would make it safer. Does it come with silicone grease? BTW we really like to look at pictures😀

Thanks.

John Davies

Spokane WA

I've only used that brand of pump a few times now and it seems fine - comparable to others I've had in the past.  This particular one does have parts / kits available to repair it, but ones I've had in the past just had the motor die after a few years of pretty heavy use before anything else broke.  I use it for different things around the house.  Examples are transferring water from rain buckets to my pool (a lot) or getting water off of my boat cover when it caves in and turns into a pool 😁.  A rainproof switch with a permanent, long cord would be SUPER NICE (and smart too)  - right now I just unplug it from an extension cord coming out of the exterior 120V receptacle on the curb side.  Definitely don't want to be standing in a puddle!  It does get warm when I run it for extended periods - like 20 minutes or so transferring water from rain buckets - so I give it time to cool down when needed.

I didn't think pictures of this setup would be interesting, but I stand corrected!  Next time I have it set up I'll update this post with a few if someone doesn't beat me too it.  😉

 

 

[JoeSyl14]

Could a valve like this one be screwed at the waste valve?  You open grey valve, once the tank is full, you open the black tank valve.  The water will fill the black tank.  When ready to dump, you open the added valve.  I saw a setup like this working in another RV.  Was wondering if it could be possible on a Ollie?!

[Overland]

16 hours ago, JoeSyl14 said:

Could a valve like this one be screwed at the waste valve?  You open grey valve, once the tank is full, you open the black tank valve.  The water will fill the black tank.  When ready to dump, you open the added valve.  I saw a setup like this working in another RV.  Was wondering if it could be possible on a Ollie?!

Not really - on an Ollie, the black tank is higher than the grey so you'd have to use a pump.

[JoeSyl14]

Ahh would have been too easy! 😉

[2008RN]

On 3/24/2021 at 10:07 AM, NCeagle said:

I've only used that brand of pump a few times now and it seems fine - comparable to others I've had in the past.  This particular one does have parts / kits available to repair it, but ones I've had in the past just had the motor die after a few years of pretty heavy use before anything else broke.  I use it for different things around the house.  Examples are transferring water from rain buckets to my pool (a lot) or getting water off of my boat cover when it caves in and turns into a pool 😁.  A rainproof switch with a permanent, long cord would be SUPER NICE (and smart too)  - right now I just unplug it from an extension cord coming out of the exterior 120V receptacle on the curb side.  Definitely don't want to be standing in a puddle!  It does get warm when I run it for extended periods - like 20 minutes or so transferring water from rain buckets - so I give it time to cool down when needed.

I didn't think pictures of this setup would be interesting, but I stand corrected!  Next time I have it set up I'll update this post with a few if someone doesn't beat me too it.  😉

 

 

 

Sorry, I know this a long time after the original posts.  I just finished my Composting Toilet install.   I really like this idea of a temporary transfer pump that does not really affect the rest of the pumping system.   I have been looking at Amazon for pumps.  There is a shurflo 3 gpm pump 4008-101-A65, and a Shurflo Strainer 255-313.  I do have a couple of questions.

1. This is about the Black tank flush system.   I noticed that there is no check valve in the garden hose inlet. Is a check valve needed?  I also  looked at the plumbing diagram in the owners manual.  It shows the tubing looping clear back around the back of the tank and then back to the side where it enters the tank. What would be the reason not to just going directly to the tank?

2. Could  you use the Zamp external charger connection in the side of the Oli for a 12V supply?

[ScubaRx]

4 hours ago, 2008RN said:

1. This is about the Black tank flush system.   I noticed that there is no check valve in the garden hose inlet. Is a check valve needed?  I also  looked at the plumbing diagram in the owners manual.  It shows the tubing looping clear back around the back of the tank and then back to the side where it enters the tank. What would be the reason not to just going directly to the tank?

There is a check valve in my flush system. Without one, poop would run out when you removed the cap from the hose inlet.

I’m guessing the diagram is not indicative of the actual route of the plumbing. Mine does not take this circuitous path. Have you actually looked underneath the front dinette seat and put eyes on it?

2. Could  you use the Zamp external charger connection in the side of the Oli for a 12V supply?

Check this connection for polarity before using.

 

[2008RN]

40 minutes ago, ScubaRx said:

 

I didn't find check valve in the outside inlet.  Maybe it is the fitting on the tank. And yes I have physically laid eyes on the inside tubing under the front dinette seat. It is routed back behind tank  then makes the turn  along the front wall, the the tube returns back and turns around the back of the tank and back up to the the tanks flush inlet.  I always figured they put other flush port on the opposite side of the tank.  It wasn't until today when I saw the diagram when I saw it just loop backs.  When I was looking under the front Dinette seat  I wondered what they just didn't tee off in the dinette compartment if the were going to plumb another flush port.  Now I am just wondering why go to all the trouble to add around  8" foot extra tubing?

[AndrewK]

I haven't seen this for myself but, the wife says the black tank flushes from two sides.

Andrew

[ScubaRx]

10 hours ago, AndrewK said:

I haven't seen this for myself but, the wife says the black tank flushes from two sides.

Andrew

That would be an explanation for the extra run of pipe and would be an improvement on what they did before with only one inlet.

[Carl Hansen]

On 3/24/2021 at 2:11 AM, NCeagle said:

I did NOT use a filter since we don't put any food / grease into our grey tank so it's soap and hair only - not a problem for the pump (as of yet).

I have a question about the black tank rinse design.  Do the rinse lines to the black tank have any kind of sprayer on the line to help clean the black tank or are they just open water lines into the tank?  The reason I ask is if there is a sprayer on the ends of the rinse lines, are they not susceptible to clogging without the rinse line being filtered?  I would be concerned about plugging up the line with hair or other particles in the grey water.
 

I very much am interested in implementing such a solution on #924 when we take delivery later in October.   I’m not familiar with how the black tank rinse systems are designed or work. 
 

Carl