| Author | Message | ||
| John and Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 229 Registered: 9-2007 Posted From: 96.42.7.186  Rating: N/A |
I wondered if there is a standard size PVC piping used for waste water plumbing in conversions. I have a sealand china toilet that is going to dump straight down into the black water tank (I am sure if I uncrate it I could find out that way also). Then the sink drains will run to the grey water tank. I am thinking the toilet probably takes like 3inch and maybe 1 1/2 for shower and sinks? Thanks in advance for the help. | ||
| Rob Norgren (Robsedona)
Registered Member Username: Robsedona Post Number: 53 Registered: 11-2007 Posted From: 75.209.23.28  Rating: N/A |
What I have 4" Toilet and 1 1/2" Shower and Sinks. It has worked just fine done in 1987 and still going Strong. Just have as much down slop as you can get to your Drain pipe. My kitchen comes to the wall up high and then drops 2 1/2 feet in 8 feet Never had a plug yet! Rob (Message edited by Robsedona on August 04, 2009) | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 955 Registered: 1-2003 Posted From: 67.142.130.25  Rating: N/A |
The toilet likely has a 3" discharge. You will also use a 3" discharge and fullway termination valve for the black tank outlet. Gray plumbing is more complicated. The trade size required depends on venting. If you use a wet vent (permitted, and common, in RVs), you need to increase one trade size above what would otherwise be required for the fixture. I recommend you download a copy of ANSI/NFPA 1192, which spells out the requirements for DWV plumbing in RV's (along with many other items, such as LP installations, heaters, generators, emergency exits, etc. -- everything, actually, except electric power, which is under NFPA 70). BTW, DWV plumbing is usually ABS, not PVC, although either is permitted. Just remember to use the proper "transition" cement if you have to join the two materials (RV-type fullway valves are not available in PVC, and you will have trouble finding certain waste sweeps and vent tees in PVC). -Sean http://OurOdyssey.BlogSpot.com | ||
| L James Jones Jr (Jamo)
Registered Member Username: Jamo Post Number: 81 Registered: 11-2007 Posted From: 74.79.237.9  Rating: N/A |
Steep is OK for pitch as long as it's very steep. The normal plumbing rule for household soil pipes is 1/4" pitch per foot. You want the liquids to carry the solids all the way to the tank. Halfway is not good. 3" is normal size for a single toilet, increasing to 4" when a second is added to the line. As for the sink/tub/shower drains, 1-1/2" is perfect for sinks & tubs. Shower stalls are normally 2". The reason to stay on the smaller side of going big is to get the water to swirl as it runs down the pipe. Swirling motion keeps the pipes clear of buildup, which you can (and will) get in a bad pitch PVC situation. Make sense? May your pipes be clear.... | ||
| John and Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 230 Registered: 9-2007 Posted From: 96.42.7.186 Rating: N/A |
All very clear and thanks for the download reference Sean, I will check that also. I shouldn't have to worry too much about pitch as I have designed the black tank to go directly beneath the toilet so there will be no problem with plugging and I made the outlets 3" on both tanks. Thanks again all. | ||
| Douglas Tappan (Dougthebonifiedbusnut)
Registered Member Username: Dougthebonifiedbusnut Post Number: 101 Registered: 10-2004 Posted From: 75.69.223.64  Rating: N/A |
Hey John, Just curious but why are you going to have a"gray" and a "black" water tank ? Why not just have one combined tank and make life easy on yourself? | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 880 Registered: 7-2006 Posted From: 75.209.81.156 Rating: N/A |
Doug...it ain't necessarily so...(one tank instead of two) I can think of a bunch of reasons why not. ...but then as our friend FF says, do it you way. BTW...how did your shower turn out?  RCB | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 910 Registered: 10-2006 Posted From: 76.192.0.94  Rating: N/A |
(one tank instead of two) I can think of a bunch of reasons why not. For sure , but don't the 2 tank advantages become moot with a campsite direct out for grey water , and using the onboard tank only for black ? FF | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1143 Registered: 12-2000 Posted From: 174.144.221.208  Rating: N/A |
"Our way" was to use a combination tank and add a diverter valve on the shower drain. This allows the shower to drain on the ground (where allowed). We do not drain sink water on the ground as it has food particles and a higher concentration of soap residue. This has worked for us, YMMV. Jack | ||
| Kyle Brandt (Kyle4501)
Registered Member Username: Kyle4501 Post Number: 506 Registered: 9-2004 Posted From: 65.23.106.193  Rating: N/A |
Lots of misunderstandings out there concerning drain pipe slope. The 1/4" per foot is the minimum that will work. The only problem with more slope is the noise from the fast moving water. The idea that the water will leave the solids behind makes no sense. Ever look at a river? Where does the water leave debris behind? At obstructions or at the bank where the water speed is slowest. I'd suggest as much slope as you can get so the drains will work even when parked in a off level spot. | ||
| John and Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 233 Registered: 9-2007 Posted From: 96.42.7.186 Rating: N/A |
Doug,the seperate tanks are mostly because I am building them from recycled 55 gallon plastic barrels and two of them fit neatly side by side in my bay. If I was buying a "premade" tank, I probably would have opted for a single larger one. I am also figuring in a valve on the plumbing that will allow diverting grey water into the black water tank to equalize usage and also as a way to "flush" the black tank when needed. | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 223 Registered: 1-2007 Posted From: 208.81.157.90  Rating: N/A |
"The idea that the water will leave the solids behind makes no sense." May not sound logical, but it is true. Neighbor thought more slope would be better. Was constant problems until he changed it. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 882 Registered: 7-2006 Posted From: 75.209.169.182 Rating: N/A |
It's true.....life's experiences...a great teacher. RCB | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 913 Registered: 10-2006 Posted From: 76.192.0.94 Rating: |
"The idea that the water will leave the solids behind makes no sense." May not sound logical, but it is true. UNtill you get to the steep point, STRAIGHT DOWN , that the RV toilet was designed to do. When there is a sraight drop , there is never a clog , in a 3 inch pipe. Even if Jimmy Carter uses your toilet. FF | ||
| Kyle Brandt (Kyle4501)
Registered Member Username: Kyle4501 Post Number: 508 Registered: 9-2004 Posted From: 65.23.106.193 Rating: N/A |
To clarify, I was refering to plastic pipe with proper (non obstructing) connections wouldn't have problems. The old rule of maximum slope of 1/2" per foot was important when cast iron was the norm. Anyone remember how rough that stuff is? Not to mention rust scale . . . . (BTW, anything greater than 45 deg was & is considered vertical.) Just who is planning on using cast iron drain piping in their bus? If the throne is a straight shot RV unit, the only horizontal runs will be sink & shower drains - I don't want to know what are you planning on doing to create solids in those lines! FF, I believe you will also need a very large black tank before turning Jimmy Carter loose . . . . | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1591 Registered: 10-2003 Posted From: 71.58.110.9  Rating: N/A |
I checked my spare Sealand china bowl toilet... it will easily take a 4 inch outlet connection. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 984 Registered: 11-2005 Posted From: 208.54.200.38  Rating: N/A |
My commode is on the opposite side of the bus from the tank (one tank only). The sewer pipe passes forward from the toilet into the next bay, then across that bay back into the rearward bay and then into the tank!! It has very little slope anywhere!! And there are two 90* Ls in the line?? According to everything I've read on the forums this won't work, but it does, even on an opposite slanted parking spot?? This thing defies all common sense. It was on the bus when I bought it but works fine. The only thing I can figure that makes it work is that we always use plenty of water to flush. | ||
| Kyle Brandt (Kyle4501)
Registered Member Username: Kyle4501 Post Number: 509 Registered: 9-2004 Posted From: 65.4.179.82 Rating: N/A |
Plenty of water is the reason it works. Most are concerned with having adequate tank size. The less water used, the smaller the tank required. (My family of 4 can go 7 days on a 30 gal black tank - & you all know how full I am!) With enough water, you can move lots of solids. If in doubt, there is a ditch in southern Az to demomstrate. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 883 Registered: 7-2006 Posted From: 75.210.51.5 Rating: N/A |
I always try...real hard...to park with the nose down a bit...(both black and grey are forward of the commode and lav)...just found it works better; and our "flush is up and over" to the drain line....we use a marine manual unit. and the sleeping is a bit better with "head high". The air levelers do their work under any circumstance, but I give them a boost where possible Haven't decided to do a macerator as yet. So far, so good... after a whole bunch of years. But, I must state, I believe the key to the drain system, even when the tanks are emptied, is a large vent line...just my way...no stink, no fuss, no muss, no bother As for dumping grey as one "camps"....we do a lot of Federal and State campgrounds...for the most part it is "verboten". RCB | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 964 Registered: 7-2006 Posted From: 74.162.73.111  Rating: N/A |
Uhmm. Shouldn't the vent pipe be larger than the waste outlet, to keep from drawing all the water out of the traps when you dump? Unlike a home system, you're emptying from a holding tank. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 885 Registered: 7-2006 Posted From: 75.211.117.232 Rating: N/A |
Guess that's a point, JTNG,...howmsoever...as in a home system, the vent from each drain point is usually 2"...the Stack larger,of course, as it goes to the main sewer or septic. Doubt that a coach system needs a large size vent (3", as the dump valves are) "food" for thought..... yuk..... Thanx, RCB | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 965 Registered: 7-2006 Posted From: 74.162.73.111 Rating: N/A |
I remember learning to keep the RV toilet flush valve open using a toilet brush, to keep the P trap water in both sink and toilet from going down the drain..... Not using the RV type might need a bit more consideration for venting, ehh? There's a big difference dumping one toilet, than dumping 50-100 gallons at once... It's easy to overlook simple things, sometimes... But you remember when the stench hits you at 70 mph toolin' down the interstate.. ("why does my kitchen sink smell like a sewer?") | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 914 Registered: 10-2006 Posted From: 76.192.0.94 Rating: N/A |
For folk with a vent setup that is marginal on the road , the first "cure" is one of the venturi roof vents that suck at speed. Sometimes just a piece of masking tape to seal the toilet bowm overflow vent will do the trick. FF | ||
| John and Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 234 Registered: 9-2007 Posted From: 96.42.7.186 Rating: N/A |
Good point John, I had not thought about the amount of air needed to vent those tanks during a dump cycle. I would think something like 1 1/2" vent stack with a T to both tanks should take care of it as you will always be dumping one or the other not both at the same time. There's always something a person doesn't think about till it's too late! | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 968 Registered: 7-2006 Posted From: 74.162.73.166 Rating: N/A |
I wouldn't dare to guess the proper diameter for the vent pipe, and much prefer to leave the specifics to the gurus here! I did note (as most all old, avid RVers have), that opening a 3"- 4" valve and letting the contents of a large tank shoot out (seemingly all at once), creates one helluva' vacuum effect on every piece of plumbing in the RV. I swore that my creation would have a vent large enough to prevent that from ever happening. (so much for swearing) Lotsa' luck. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 986 Registered: 11-2005 Posted From: 208.54.200.14 Rating: N/A |
The solution to a smaller vent pipe is to dump in short stages or dump slowly. Or, a large cap could be added to the top of the tank to be opened when dumping. Or, the toilet could be left open with the water shut off. Stages are probably better because full flow sweeps out the solids better. In any case, refilling the traps is a pretty simple operation. This is not a big problem! | ||
| Randy Davidson (Rdavidson)
Registered Member Username: Rdavidson Post Number: 27 Registered: 7-2006 Posted From: 70.105.229.11 Rating: N/A |
I have a 200 gal black/gray tank and it dumps VERY fast using the normal 3" valve and pipe. The vent is very small (one is 1" the other 3/4"). Never pulls the traps. Remember the density of air vs. water... you don't need much vent to move a LOT of air. IMHO. | ||
| don goldsmith (Bottomacher)
Registered Member Username: Bottomacher Post Number: 259 Registered: 12-2000 Posted From: 72.152.141.211 Rating: N/A |
Vent pipe sizes in the USA have always been a bit overdone, if the rest of the world is any indication. In Europe, a 1" vent seems to take the place of the normal 2" vent in most instances. If you want to dump your tank and leave the vicinity, you may have a dry trap. But if you just wait until the dump is done and refill your traps, you'll be all right. |
