Plumbing Glossary

Terms used in the descriptions of plumbing items and their use.

Bottom Drain
Bottom Drains can help in keeping a pond clean. Installed through the liner in the bottom of the pond. They can be connected to a filter or to a sump where the waste from the bottom of the pond can be flushed away.

Bulkhead Fittings
A special plastic fitting to provide a watertight seal through a plastic container or a flexible pond liner. This fitting also allows full flow of water and the ability to attach flexible pipe with the use of a male adapter. The fittings have left handed threads to keep the fitting tight when installing the male adapter.

Installing Bulkhead Fittings
Remove the sealing gasket and use it as a pattern to cut the hole.

Place the gasket over the area where the bulkhead will be installed and mark on the inside of the gasket. When cutting the hole in hard plastic or fiberglass it is best to use a hole saw. Use a breakaway type knife or other small blade sharp knife to cut a clean hole when installing the bulkhead in a flexible pond liner.

The bulkhead can be installed with the nut on the inside or the outside of the liner.

Apply a bead of silicone sealant to the gasket and place this on the wet side of the installation. The sealant will act as a lubricant to keep the liner from bunching up and also help to create a watertight seal.

Tighten the nut to the point that the gasket is crushed against the liner.
Install a male adapter to attach your plumbing to the bulkhead. You can then glue pipe into this adapter to finish the installation.

We recommend the use of flexible PVC pipe to allow some movement to relieve any stress that could be exerted on the bulkhead fitting.

Couplings
Couplings are used to attach one piece of pipe to another. These may be the same or different sizes.
Unions
Like a coupling, these join 2 sections of pipe together. But these are used as an easy way to disconnect the pipe without cutting. These are used to be able to quickly an easily remove a pump or other device.

Flexible PVC Pipe
Flexible PVC is a very strong pipe that is easy to work with. It glues into standard schedule 40 PVC or ABS fittings. It provides more water flow than you would have from using rigid pipe and elbows by reducing friction loss/

Hose Clamps
Hose clamps are used to keep tubing attached firmly to the barbed side of a male insert.

Male Insert
Used to connect flexible tubing to a pipe or a device. One end is threaded and the other is barbed to hold the tubing.

Plumbing Terms:

Slip - Glues* to fitting or pipe
FPT - Female Pipe Thread
MPT - Male Pipe Thread
Bushing - a part that is glued* or threaded into a fitting such as a coupling or elbow to adapt to a different pipe size.

*When working with PVC and ABS pipe always use the all purpose glue.


Valve, Gate
A gate valve is also called a knife valve. They are easier to use than a ball valve for fully opened or closed operation. Not for regulating flow.

Valve, Ball
Used to regulate water flow through a pipe. Allows for complete flow when fully open.

Valve, Free Flow Check
Use to provide flow in one direction only through a pipe. When installed before an external filter it keeps the dirty water in the filter from flowing back into the pond if power is lost. Also to keep an external pump primed if power is lost.

Spring type check valves should NEVER be used in a pond installation.