Pecos SWW<>The Other Reason Why Your Irrigation Valve Might be Leaking

The Other Reason Why Your Irrigation Valve Might be Leaking

Diagnosing why your irrigation system leaks can be frustrating. Take a look at section four of the troubleshooting guide on the Rain Bird Web site and you will see a number of possible causes including a worn or pitted valve body. I even called Rain Bird to ask what might be causing my valve to leak.

There are only two user replaceable parts other than the valve body itself that could have been causing the leak - the solenoid and the diaphragm. The solenoids were less than two years old so I suspected the diaphragms.

I was surprised when I replaced the diaphragms in my 12 year old Rain Bird PEB/PESB valves and the valve continued to leak. The valves are professional valves and Rain Bird claims them to be durable and long lasting at pressures up to 200 PSI.

The original installation was done by landscaping "professionals" and they did a good job but they failed to install unions which meant that the 3/4" PVC pipe had to be cut to remove the offending valve.

I sought professional help. I cut the PVC valve out and visited my favorite irrigation parts store here in Tucson, Irrigation Sprinkler Supply Company. Note: Irrigation Sprinkler Supply Company appears to have closed their doors and is no longer doing business. The expert there noticed the problem immediately - a hairline crack in the valve body. I was surprised and impressed. I had completely missed the small hairline crack. I decided to replace all three valves and the expert recommended the Rain Bird DV series valves. They were about 1/3 the price of the PEB/PESB valves I was replacing and he told me that they had good luck with these valves.

A leaking valve can be hard to discover, diagnose and replace. It is probably discovered when you receive your monthly water bill as occurred in my case. It is not, however, a project you should put off. A doubling of your water bill can make a big hole in the wallet.

You can determine if one of your valves is leaking by checking the lowest emitter in your system for water flow when the valve is off. It is normal for water to drain out of the system after the end of the on cycle so wait 30-60 minutes before checking the emitters.

I decided to build the irrigation valve assembly myself. It turned out to be a much more complicated engineering project than I had thought it would be.

Note: Not shown in the picture is an anti-siphon valve located above ground in-line with the supply line. It may be required to meet local building codes.

This is a list of the parts I needed:

1 - 3x 1" Rain Bird DV valves
2 - 2x 155 mesh Y-filters
3 - 2x PVC unthreaded T-connectors
4 - 1x PVC unthreaded 90 degree L connector
5 - 2x PVC 1" male threaded to 3/4" female threaded adapters (valves to Y-filters)
6 - 4x PVC 1" male threaded to 3/4" female unthreaded adapters (3 for supply side pipe to valve and 1 for outlet side)
7 - 2x 3/4" male threaded to 3/4 female unthreaded adapters (union to PVC pipe)
8 - 3/4" Schedule 40 PVC pipe
9 - 1x Gray union (Ace Hardware)
10 - 1x White union (Home Depot)
11 - 2x Senninger 20 PSI pressure regulators
PVC primer
PVC cement
Plenty of Teflon tape

There are a number of items that you have to get right or you will have a bad day:

The valves must be oriented properly. The flow direction should be marked on the valve.
The PVC pipes must be cut to the proper length.
Schedule 40 is recommended for non-threaded applications and schedule 80 is recommended for threaded applications. PVC primer should be applied before PVC cement. Reference - see Plastics Technical and Installation Manual (PDF).
The proper PVC primer and cement must be used
Any filters and pressure regulators go on the outlet side of the valves
According to The Urban Farmer Store Drip Irrigation Handbook, three wraps of Teflon tape are required on all threaded connectors
Don't forget to insert the threaded union connector before cementing in place!

I printed out the numbers 4, 5 and 6 and taped them onto the valve assembly with 2" clear Scotch shipping tape. They denote the station controller program number for each valve. If you must use narrow tape, use more than one strip of tape and do not leave the paper exposed where it can become wet and moldy.

Take a closer look at the image above and you will see two lines that are different from the third. The top two lines are 1/2" drip line irrigation to trees and plants. Y-filters are added after the valves to strain out any foreign matter that might clog one of the emitters. Pressure regulators are then put in-line to reduce the pressure to 20 PSI.

The third line goes to lawn sprinklers and needs no filter or pressure regulator. It does need a union, as does the supply line, so the entire valve assembly can be easily added and removed.

You have to be very careful cutting the PVC pipe to size. Assemble without PVC cement first and set the assembly in place to verify for fit before cementing the pieces together. Wetting the PVC pipe with water will help ensure that the PVC pipe is fitted completely into the connectors. Be sure to dry and clean all fittings before applying primer and cement. Follow the cure-time before moving or applying water pressure to the fittings. The PVC cement I used requires 15 minutes before handling and two hours before applying water pressure.

The Rain Bird troubleshooting guide doesn't mention that a cracked valve body can be the reason for your leaking valve. It is relatively rare, but be aware that can happen.

Building your own irrigation valve assembly can be a fun, but challenging project. Plan carefully and take your time to get it right the first time.

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