Holding Tank Capacity?

[rip]

I had my tanks custom built with 160 fresh,65 grey and 40 black. I can get about 10 days tops due to our black tank being small.If I had to do it again,I would have 70 black and 40 grey.I agree you can dump grey almost anywhere using a garden hose.My fresh tank sits on my bay floor and six inches shorter than the  length of the bay.My grey and black sit on top of my fresh tank and my black overhangs my fresh tank which allows my hookups for the dump valves.
    Don

[Len Silva]

A lot of your decision has to do with your intended use.  We like state parks which usually have water hookups but not sewer.  We don't do a lot of pure boon-docking.  So for our purposes, 50-60 gallons of fresh is plenty, but holding tanks can never be big enough.  I prefer separate black and gray tanks at about 60:40 or 70:30 range and as large as possible.

Len

[kd5kfl]

greywater tank 20% bigger than feshwater tank. so yo don't find yourself taking a shower ankle deep in gray sulfurous water

[redbus]

We have 100 gal.fresh and 100 black/ grey combination tanks. We can go 8 to 10 days before dumping and taking on fresh water. We boondock 5 or 6 months a year with NO dumping on the ground[/u]

[cody]

We have 100 gallons fresh with twin 85 gallon tanks for grey and black, they are mounted side by side within a 2x12 cradle, the dump valves come off the ends and have a common pipe that dumps to the hose, this requires 3 valves but enables us to use the grey to flush the black tank, very simple but nice setup.  Because I mounted them side by side I have a piece of 3/4 inch plywood for a tank cover that allows me to use the 2ft above the tanks for additional storage.

[Dreamscape]

Doug,

We have 100 gal fresh, one 100 gal gray/black with a gray diverter pipe to the outside under the bay, which we have not used.

When/if we change it will be 100 gal fresh, with a larger combined tank for gray/black. I like the combined tanks, but it all depends on your intended uses.

Just remember to size your tanks to leave you room for all of the other stuff, storage for camping supplies chairs etc., hot water, propane if you will need it, inverter and batteries, tools, and a variety of oil, cleaning supplies and anything else you want to take with you.

Paul

[cody]

The tank sizing was a big issue for me, thats why I got the ones that were 24 wide and 72 long, that allowed me to place 2 tanks side by side within a cradle and still put a piece of 3/4 inch plywood on top, I did loose a foot of storage across the bottom but I still have 2 feet of storage on top of them.

[Doug1968]

Fellows,

I appreciate all of the feedback. Sorry for the delay in responding but I have been away from the board for a few days.

Sean - TomC

I like the idea of the warm up valve. Very ingenious and a good idea. I will plan on installing this feature regardless of what I do with tanks. Did you install a switch at both the bath and the kitchen?

KD5KLF

Makes sense to have the gray tank larger than the black. Possibly extra fluids will get dumped into the sink, ice, soda, beer!! NO NOT THE BEER, and I can see where you might run out of room if not careful. 20% bigger makes sense.

Cody

On your 24" x 72" tanks, what was the tank height? My bus is 102" wide and I think I could fit a 96" tank across the bus? It would be nice if I could find a stock, off the shelf size that utilizes most of the space?

I have been following a post regarding mounting the plumbing to the tank. It seems as though these fittings would be readily available along with the tanks?

Does anyone have a good source for the tanks and the fittings?

Also, is it best to have the toilet drop straight into the black tank?

Would it be good to install a removable cap on the opposite side of the drain for rinsing out the black tank? Or would it be located on the same side as the drain so that it could easily be accessed when draining the tank?

Is there a standard location for the drain? Drivers side or passenger side?

I appreciate all the input and I look forward to your responses.

Thanks,

Doug

[John316]

Doug,

First about plumbing the tank, if you get stock tanks, you probably will be able to use those standard rubber grommets (that I posted a pic of). We ended up using a router, and shaving that area down, that way the tank is "thinner" right, exactly where the grommet is. I will try to post pics.

We went with a toilet straight drop. That is what was recommended to us, and makes sense to me.

We have a fitting installed on our black tank for rinsing. We have it to where you connect the hose up to an outlet and it fills up the black tank....That place where we have the connection so we can rinse the black tank will be right with all of our other hookups.

We found that most of the dumps, and hookups, to be on the driver side. Our old setup was on the passenger side, and that was a pain!

If you have anymore specific questions, let me know, since we are working on it right now . I am not saying that my answers will be correct, however, they will by my way .

God bless,

John

[cody]

Doug, our tanks are about a foot tall, on the 96 inch tanks you may not have enough room to put the drain fittings and valve on the end, that has to be figured into the installation.

[Dreamscape]

Doug, You want all of your hookups on the driver side, water, elect. and sewer.

Figure what size tanks you need, measure the area and look at one of the advertisers in the BCM magazine. It usually is a full page spread, made in CA and shipped to you. They may have the sizes you need, otherwise shop locally for a supplier. I do not have the experience others have had because our waste is a round aluminum tank, which is not very space friendly, installed by a PO. The plastic ones also make it easy to attach sensors to show how full they are, and are translucent enough to see the liquid levels.

Paul

[DMoedave]

We used tankdepot.com and they ship from Wis. or Ca we picked one that shipped from wis  cause shipping $. We picked up a 55 gal for around 230. then 4 fittings another 30. then shipping to NY then tax! it was right at 320. total but they send you just what you want. They have shipping calculators and give sizes and drawings. You have to mark the drawing and send it to them by email or fax. They shipped right away. Make a luan or cardboard template and make sure you have all the fittings where you want them. We put 2 3" ports and 2  1-1/2 fittings. I dont think they did 2" for some reason. These were all female pipe thread so you use pvc male adpts.

[JackConrad]

If you are in the Southeast, try DuraCast in Lake Wales, FL. They make many different sizes & shapes of rotational molded tanks and spin weld the fittings you want where you want them.  Jack

[Sean]

I like the idea of the warm up valve. Very ingenious and a good idea. I will plan on installing this feature regardless of what I do with tanks. Did you install a switch at both the bath and the kitchen?

Because the valve allows the hot water to come all the way to the fixture, there needs to be one on each fixture where you want to do this.  We have three; one for the shower, and one each for the kitchen and bathroom sinks.  I used irrigation valves, made for 24vac but work fine on 24vdc.  There is a push button located at each fixture; I used pinball-machine flipper buttons, which mount nicely right through the wood of the cabinetry and have a finished appearance without any trim plate or switch cover.

Does anyone have a good source for the tanks and the fittings?

We used Ardemco; when you buy their tanks, they include any number of fittings pre-installed that you'd like for no charge.  The fittings are made of the same polyethylene as the tanks and are spin-welded in.  You need to know exactly where you want them before you order the tanks, and send them a drawing.

Also, is it best to have the toilet drop straight into the black tank?

Yes.  In fact, if it is not a straight shot, you may have problems with a standard RV toilet.  Our tank is a good 10' in front of the toilet; we use a Microphor air-flush model which uses two quarts per flush, and sends the waste to the tank under pressure through a 1.5" line.

Would it be good to install a removable cap on the opposite side of the drain for rinsing out the black tank? Or would it be located on the same side as the drain so that it could easily be accessed when draining the tank?

We have removable plugs in the center of the top of the tanks, just in case.  In five years of full timing, we have never had to use them.

We installed a third fullway (gate) valve in the dump line, downstream of the T where the black and gray lines come together.  When at the dump, we first drain the black tank, then close the downstream valve and open the gray valve, which allows the gray water to flow backwards into the black tank, flushing it out.   We then close the gray and open the exit valve, draining the flush water.  We do this two or three times until the effluent is gray rather than brown; a 2", 45° clear plastic bayonet fitting on the hose provides the view.  Then we close the black valve and open the gray, allowing the rest of the gray water to flush out the hose.  Using this strategy has kept the black tank free of sludge buildup.

Is there a standard location for the drain? Drivers side or passenger side?

Motor homes must have their dump lines on the driver side, per ANSI/NFPA 1192, and that is where you will find most park connections, as well as the orientation of most dump stations.  However, passenger buses universally have their dumps on the curb side, and that's where you will find dumps in bus garages.  In five years, we've dumped in a bus garage only four times.  Since bus dumps are basically hoppers with grates over them, the effluent will splash a bit -- stand well clear when you pull the valve.  Also, to use this sort of dump, your drain needs to come pretty much straight down out the bottom of the coach, or else you will have to fiddle with a hose somehow.

BTW, our dump is on the street side, as normal.  To use a bus garage, we just back into it.  What has been more useful for us over the years is our built-in macerator pump and a 50' hose.  We have a separate set of 1.5" fullway valves on the curb side going to the macerator, which lets us dump into household toilets, pit toilets, sanitary sewer manholes, and dump stations too far to reach with the normal gravity hose, or actually uphill from the bus (don't laugh, it's happened).

-Sean
http://OurOdyssey.BlogSpot.com

[BG6]

Fellows,

I am working on a layout for my holding tanks in my 102A3. I would like to have enough storage to support two people living in the bus in the boondocks for 16 days. This would include fresh water.

You're looking at between 100 and 200 gallons, depending on whether you use water like a backpacker or like you're hooked to the shore tap.

You need at least two tanks (culinary and sewage), unless you're not too picky about  your water tastes.  Most people go to three tanks (culinary, greywater and blackwater).  Remember also that you need 50% more sewage tank than culinary tank (you are adding solids to the blackwater, and these take up a lot of volume).  The advantage of a single sewage tank is that this is the most efficient (you aren't going to find one tank full while the other is half empty), the DISadvantage is that you are forced always to find a dump station, while greywater can be drained in many more places, if you need to.

You also want to spend the extra money for BAFFLED tanks, if they are available.  Imagine that you have a half-empty culinary tank and a half-full sewage tank.  You're carrying maybe 3/4 of a TON of liquids, which are free to slosh around (this is known as "ullage").  You have to hit the brakes and stop from highway speed.  All of that liquid is sloshing around, first to the front of the tank, then rocks to the back, then back to the front.  3/4 of a ton, against the couple of hundred square inches on the front of the tank.  Can your tanks take it, over and over for years to come, without failing?  And every tanker-truck driver can tell about the time that his half-full tanks sloshed him forward another foot or two after a stop, and these tanks are baffled!

Few plastic tanks are baffled, but you can still beat the laws of physics by using several smaller tanks instead of one big tank.  Smaller tanks for culinary water also give you the ability to increase or decrease your freshwater load, if your needs change.