You are here: Home > Holding Tanks for Sewage & Water > Sewage & Water Holding Tank Q&A


Holding Tank Q&A

Question:
Where should I put my fittings?

Answer:
All tanks start blank. Your fittings can go wherever you need them for your application. You can be very specific if you need a fitting distanced away from any wall or another fitting. The manufacturer will put them as close as possible to your requirements.

It is recommended to have all your fittings on the top of the tank. But if you need your vent and inlet to be on the side of the tank make sure they are as high as possible.

A Diptube for your discharge is the most popular choice of discharge (at extra cost). A Diptube is a stand pipe that goes from the top tank, inside of the tank, to the bottom for a more efficient pick-up of waste (indicated in the photo above). If you need your Diptube on the upper side of the tank they do provide a 90° pipe for that application. If you want a Diptube on an odd shaped tank make sure it is reaching the lowest part of your tank. Otherwise any bottom fittings for discharge are still an effective and common way to discharge your tank.

Any fitting on the very bottom of the tank (for gravity applications) is creating risk of clogging. I would do as big as a 3-inch fitting and run PVC off of the tank if possible because it does not permeate (as that line will essentially have constant waste in it between pump-outs)

Question:
What size fittings do I need?

Answer:
Most sanitation lines are 1.5-inches. There are only a few applications that are 1-inch sanitation lines. Make sure you verify what you have existing or are planning on using when deciding the size fittings you will need on your tank.

Vent lines are for air displacement only. Therefore the bigger the better. 5/8" and 3/4" are the most common size vents for waste tanks and you can go as low 1/2" for water tanks as the displacement is less rapid.

Question:
Do I need separate inlets for two toilets?

Answer:
You do not need two inlets if you have two toilets. You can have the lines join together before the tank into one inlet. But if you are worried about clogging or just want to prevent any chances of clogging due to multiple head use at the same time I would recommend putting two separate fittings.

Question:
Do I need separate discharge fittings to go to my Deck Plate and to my Overboard discharge?

Answer:
You do not need two separate fittings to go to the Deck Plate or Overboard discharge. You can put a fixed Wye or Tee fitting to divert the waste in the direction of discharge. But if you are more comfortable having one fitting for each discharge it is a common occurrence to have one for each.

Question:
Do I need an Inspection Port on my tank.

Answer:
It is not necessary to have an inspection port on your tank. If you decide you would like an inspection port on your tank it is recommended to not go over a 3-inch port. Anything larger may weaken the integrity of the tank as the heat from the "Spin Weld" can bow the tanks wall.

Question:
How thick are the tanks?

Answer:
The tanks are a minimum of 3/8-inch thick at it's thinnest place.

Question:
Do Polyethylene tanks permeate odors?

Answer:
Polyethylene does not permeate waste odors. If you have odors in the holding tank areas please check your hoses for permeation by wiping the lines with a slightly damp rag and smelling the rag. If you smell waste, the lines need to be replaced. If you've and any overfilling issues check all of your fittings and make sure to clean up any waste that may have come out any paths of least resistance (threaded fittings and vent line)

Question:
How are the FPT (female pipe thread) fittings put on the tank?

Answer:
Nothing sticks to Polyethylene. Therefore they take a FPT Poly fitting and do what's called a "Spin Weld" to the tank. It is a friction weld that adheres (melts) the fitting to the tank.

Question:
Do the tanks have seams?

Answer:
Our tanks are Roto-Molded. They do not have any seams. There is a single hole left on the tank from creating the mold and that hole is patched with a "Spin-Weld" poly patch.