plumbing questions

I am now to the stage of plumbing and have a decent understanding of it and I have a plan on what I am going to do with it.  I just have a couple of questions before I go any further.  First is about the drain.  I have seen on RF some setups for the drains that have a pipe running from each sink into a hopper( four seperate drain pipe)  Is it okay to run all the drain pipes into one pipe and then T it into one single pipe that drains into the hopper? 
Second is about the supply line that runs to the heater.  I understand that the supply comes from the pump into the cold side of the heater and then a line from the hot side to the hot side of the sinks.  Where do I tap into for the cold side of the sink? I am guessing that you T off the supply before it goes into the heater. 
Much thanks
B.
 

My cold water is T'd off the pump to the sink and heater.
As far as the drains, what does your HD require?
Do they require an air gap before the waste tank, or can you plumb direct?

Only do the air gap into one hopper thing if your HD requires you to. My HD did not require it once I explained that if my grey water tank fills or clogs I would be getting grey water all over the trailer. She felt it would be best to only have the air gap at the faucets in the sinks. Much easier to see and safer if the sinks do not drain in the case of a full or clogged tank than under the counter in a stupid little funnel (A totally silly system if you ask me).
 
On another note be sure your grey water tank has its own vent or your drains will not flow properly - don't ask me how I found that out.

Somewhere in this batch of pictures is how I did my plumbing a few months ago.
https://picasaweb.google.com/103200304792624046939/2008_05_05#

So many dead ends.  I have come to the part of the plumbing that deals with the drains.  I am wondering how to make the connection to the waste tank from the trap which is pvc and the material of the tank is some kind of plastic.  How is this connection made?  I've seen photos with the pvc right up to the tank.  Can these two material me glued together?
The waste water tank has 3- 3/8 female ports, I plan on using one of them to drain the tank.  I have read on RF that 3/8 is trouble.  Can these ports be cut off and something else attached or can they be drilled and tapped for a larger male fitting?
If anyone can post a close up of their system and maybe a description of it that would help me and I'm sure loads of others.  I am the type that does well with visuals.  Thanks B.

Drill into the top tank the size of your drain pipe, silicone the crap out of it, rubber gasket, more silicone.
Ditch the 3/8, way too small. The first bit of food that gets in your tank will plug it up.
Go to a plumbing supply, ask about fittings.
There has to be something with a flange and nut that you could use. Or find a place that does plastic welding....

I got a rubber grommet from P&P Moterhomes. Drilled a 2 1/2 hole in top, installed grommet with a little dish soap then inserted drain pipe through it, it was easy.

You could also use an abs rv waste tank which is easier to glue a threaded fitting to.

indycarver1
 The waste water tank has 3- 3/8 female ports, I plan on using one of them to drain the tank.  I have read on RF that 3/8 is trouble.  Can these ports be cut off and something else attached or can they be drilled and tapped for a larger male fitting?

 
ok, i dont think you have a "dedicated to waste water tank" the reason for the three small ports is supply connections and venting for filling, you probably have one small port on each of three corners im assuming, one of those "on the bottom" is for supplying "fresh cold" water to a pump to supply your system.....
the one that is on the top corner would be for venting the air while filling the tank.....
and the third small fitting on the other bottom corner is for installation issues..... mounting tank on short side/long side..... that one would usually be capped off.... or it would fall into the vent or supply position depending on how you mount the tank.....
the large hole is for the "fresh water fill" and it would need to be in one of the top corners or top side if using the tank for fresh water......
since you are using the tank for grey water, you will only need one of the small fitting for a vent.... run it up to the roof.... it will help with draining trust me... the other three (2 small 1 large) get capped off.....
 
you then go to the rv store and pick up a flanged tank fitting, mount it to the tank and plumb it up !
 
and yea, your waste tank drain needs to be at a very minimum the same size as your drains into the waste tank itself..... i would go with standard size drain(3" i think) to guard against plugged drain lines.....
the last thing you want to do is have to rooter out a clogged drain on a truck/rv/trailer.....it gets messy real fast !!
 
i would also recommend a drain valve such as this one..... it will let you blow back through the system to flush it out or bust up a clog in the pipes........
 

Thanks for the reply and some great info.  But I need some clarification on one point..."pick up a flanged tank fitting, mount it to the tank and plumb it up"
By mounting it to the tank you mean cut a hole in the tank and glue it up?  Would the materials (tank and fitting) be glued with an all purpose cement?  And would this hole have to be as close to the bottom of the tank as to drain the contents?
And is this the flanged fitting in the picture?
Thanks B.

the pic i posted would be at the working end of the drain.... where you hook up a drain line to empty the tank....
 
in a perfect world, the drain connection at the tank would be at the lowest possible location on the tank..... remember to take into account the "rake" of the vehicle itself when mounting the tank (you dont want to mount the drain at rear of tank, and the truck sits nose low, you will always have standing grey water in the tank then)
 
easiest route would be buying a "grey or black water" tank,  the fittings will already be in place......
an after market "retro fit" flanged fitting would have a large nut on the back of the fitting, you would cut the appropriate size hole, put the nut inside the tank (force it through the hole you cut) and place the threaded end of the fitting into the hole..... reaching through the fitting(using fingers) thread the nut onto the fitting and tighten down, using the appropriate sealers and/or gaskets the fitting calls for..... use black drain lines/fittings and everything will glue together like it should and you will be in business !

for some reason i am having trouble figuring out the proper search phrases to find a picture of the fitting.......but you should be able to go to your local rv center and find a retro fitting

here we go...... this is the style your looking for..... this one is from a koi pond dealer.....
you might need to cut an access hole in top of tank to install this, then use an inspection port to close off the hole up top.....

 
 
http://www.manorkoi.com/connectors-pipework/tank_connectors/63mm_-_2inch_threaded_tank_connector_heavy_duty

Ive seen those fittings for the drain. But what is an inspection port? I was Wondering how i was going to reseal the top piece after making a hole to install the bulkhead-type fitting for the drain!

Thanks for the information.  Here is what I did.  Before I posted this question I contacted the place where I got my tank and asked them if they had an idea, just for ****s and giggles, they told me that they have had customers use a shower floor drain(slip pvc fitting) and use it upside down.  I cut a hole where I wanted to mount the fitting.  I ran bolts through the fitting and the tank wall and siliconed and it seems to be a good idea.
The fitting that you suggested is very similar.  The differences are that the shower fitting is not threaded with male and female and I had to drill and bolt.
I have posted pics on my flicker.  I can't seem to upload straight to  my post hear.  I will keep posted on how it works but I really looks good.
Thanks again for all your help.
B.

This fitting that I am using is for the waste in and I turned the tank around to use the larger nipple as the waste out.  I know I asked a couple of questions earlier and since I have made some adjustment to my sytem.
My flicker link is in one of the posts above.
B.

aarrgghhh...lol, that 30/30 thing kills me, lol
i do see the benefits of it though, with all the spam posts we ger already i would hate to see this place wide open!!

lol, it figures i would find this after the fact.... here is a complete kit that covers inlet, supply, vent, and inspection port.......big boat stuff, lol...im just sayin  
 

 
this would be for a fresh water tank with no nipples to start with..... but a good shot of what a basic inspection port is...... lol, i think thats installer speak for cut a big hole to be able to reach in and work from the inside as well, lol

flicker dot com [link=mailto:photo/63694646@N0615805541662/in/photostream]photo/63694646@N0615805541662/in/photostream[/link]
trying to link my flicker.

I think I may give up on trying to post pics
Sheesh!!!

Type in flicker pics or something, hilight it the, insert link will appear in the tool bar, click on that, insert your copied link to that. Hit insert.

indycarver1


I think I may give up on trying to post pics
Sheesh!!!

When your in Flickr. Click on a photo you want to add to the post. On the photo's page, there will be a little social media tool bar with mail, facebook and twitter icon. At the end of the little tool bar there is a downward arrow, click this and you will see the code that you can cut and paste. Once you click on the code it will highlight everything, you cannot just select a piece of the code so copy it all. Paste the code into notepad or some other text editor and than cut out just the link for the photo "http://farm7.static.flickr.com/6038/<filename>.jpg". Than click the image link button here in the forum and paste the link.

Try again
http://www.flickr.com/photos/63694646@N06/5869189281/
http://www.flickr.com/photos/63694646@N06/5869185915/

i only have 1 question...well, two.....
 
1st, why did ya turn those white walls in ?? i think that would really set her off...
 
and second, how are you exhausting the genset?? through the floor ?  into the truck exhaust? im looking at one now that intakes and exhausts from underneath

I know. I thought the tires would be real cool looking but they are in pretty bad shape.  Getting new rims and tires sometime soon.
Yep the generator is open throght the floor. and the exhaust is run out the driver side just behind the driver door.