Vents for Water Tanks

Holding tank vents are nothing more than a abs pipe thru the roof connected to a separate fitting in the top of the tank.
For a 2" grey water drain, needs a 1" or bigger vent pipe
For a 3" black drain, the vent pipe should be 1 1/2" or larger.
Then, like on RVs, the vent pipes could have a roof fitting mounted over them to keep leaves etc from falling in.
If the vents are not big enuff, no bigee,.....it will just suck all the sink traps dry, and you will wonder where the smell is coming from,....a problem on some RVs.

The FWT vents thru the filler fitting, or a separate fitting like this

32vld wrote:
I got it figured how to vent the fresh water tank.

Not sure how to vent the gray water on the truck. In a house there is a cesspool vent when the line reaches the house. Then the drain pipe has a vent to the roof.

Will there just being a vent on the gray tank be enough? The tanks are only going to be 5' from the sinks.

Told my son that there has to be traps from the sinks to keep air/smell rising up the drain from the holding tank.

Is there anything I am leaving out?

Thank you to all that have helped.

Well you're lucky to have this Forum with folks that freely give explanation and help.

Your waste tank will need a vent to the outside of any structure you put on the truck's frame. Typically, they consist of a 1 1/2" ABS or PVC pipe attached to a tank fitting or through a tank grommet and led though the roof. This allows for venting of any gas to the outside at the top of the structure where winds bear it away.

Installing air admittance valves on any sink drains would be a good idea. When in transport, the traps can be emptied by the sloshing of water in the traps, leading to bad odors inside.

Plans approved???

I got it figured how to vent the fresh water tank.

Not sure how to vent the gray water on the truck. In a house there is a cesspool vent when the line reaches the house. Then the drain pipe has a vent to the roof.

Will there just being a vent on the gray tank be enough? The tanks are only going to be 5' from the sinks.

Told my son that there has to be traps from the sinks to keep air/smell rising up the drain from the holding tank.

Is there anything I am leaving out?

Thank you to all that have helped.

I don't know but take a look at these, might help I don't know?

https://www.google.com/search?q=food+truck+water+vent&biw=1093&bih=502&source=lnms&tbm=isch&sa=X&ved=0CAcQ_AUoAmoVChMIjPKj3Y6vxwIVVDKICh2etQbh

32vld wrote:

gbopp wrote:
What type of RV do you have? I thought all the water tanks were vented.

If you read my plumbing post you would of seen that my son is building a food truck.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28522245.cfm

He bought two plastic tanks. The do not have vents on them.

I was not aware of your previous post. I was just trying to answer the question you posted.

The air vent on my fresh water tank is just a hose attached at the top and routed down under the floor. It doubles as the overflow as well.

Black/grey tanks aren't vented directly, but the plumbing attached to them is, just like on a house. Up and through the roof.

As long as you have SOME way for air to get in/out of the tanks from the OUTSIDE of the vehicle (don't want smell tank air in your truck...) it should work ok. Building it to code for a food truck may be a different animal.

Yes it is. We submitted plans prior doing the build with the board of health and received approval.

However we have be doing most of the build work ourselves except for the welding/metal fab work. And we have an automotive and camping background. We are not RV/food truck experts.

Is there a special vent?

Where can we buy them?

Yes, you'll need vents on any tank that needs to be filled or drained. The air inside the tank needs somewhere to vent. This is usually accomplished with a fitting on the tank and the appropriate piping, typically located at the top of the tank.

Is this "food truck" a commercial endeavor?

BTW, it might be a better idea to have all of your questions in one thread rather than multiple threads asking about each item individually.

gbopp wrote:
What type of RV do you have? I thought all the water tanks were vented.

If you read my plumbing post you would of seen that my son is building a food truck.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28522245.cfm

He bought two plastic tanks. The do not have vents on them.