Leaks in the Head Assembly Components

To determine which item is leaking, each head assembly component could be removed one at a time to find the cause of the leak. To start, try removing the backflow preventer and run the system. If the leak continues, replace the backflow preventer and remove the filter, then the pressure regulator, and so on, until the leak stops. This may help to determine exactly which item is causing the issue.

We recommend ensuring each part has a washer installed before installing, that is if you are using hose thread fittings. Pipe thread fittings do not use washers and are not compatible with hose thread fittings. Hose thread fittings are not to be used with Teflon Tape or Pipe Dope, as this could cause leaking between the connection. Checking your threads on all of your devices is also recommended, as damaged threads could be the possible cause of leaking. 

Troubleshooting Each Leaking Item

Backflow Preventer: The backflow preventer is designed to release water when the watering cycle stops or the system is turned off, so you should see dripping from it at system shutdown; it should not be dripping constantly. 

To troubleshoot this part, the first thing to check is the O-ring. O-rings deteriorate over time and need to be replaced periodically. Make sure the O-ring is seated all the way down in the part. Another cause for a leaking backflow preventer is incorrect placement in the head assembly. If it is placed upstream from a timer and the system is not being used but the hose is on, pressure will build up, which can destroy the backflow preventer. To relieve some of the pressure, water will leak from the relief holes. If a timer is used, it must always be installed first, before the backflow preventer. Remember to hand tighten these parts only and do not use teflon tape or pipe dope on hose thread connections. If you over tighten them, it can ruin the O-ring seal or cause cracks that cause leaking as well.

Filter: The filter should not leak. Depending on where the leak is you’ll want to check that the o-rings are present at the inlet (if it has hose threads, pipe threads do not have o-rings) and the canister body (if applicable).  All of the filters that we sell come with removable screens that can be cleaned. It’s important to open up your filter and check the screen. If you notice buildup on the screen, the screen should be removed and cleaned. Once cleaned, put it back in and close up the filter unit.  

Pressure Regulator: Some pressure regulators have a small hole in the side of the preset regulators that acts as a relief valve. A little water dripping out is normal. If you get a steady stream out of this hole, seal it with your finger and then let go. Repeat a few times and see if it stops leaking. This helps the new diaphragm seat itself. Please note the Senninger brand does not have this small relief port. Also try turning the system on and off a few times. If it is still leaking, check the water flow direction. If the water is flowing in the right direction and the above steps didn’t work, then the device is most likely defective. 

Another cause for leaking could be the placement of the pressure regulator within the head assembly. If you are using a timer, it must be installed first, followed by the backflow preventer, the filter, and then the pressure regulator. Also, remember to hand tighten these parts. If you over tighten hose threaded parts, it can deform the rubber washer seal and cause leaking, plus over tightening of plastic parts may cause cracks that cause leaking as well.

Leaks in Other Areas of Your Irrigation System

Fittings:  First and foremost, assure compatibility between fitting sizes and tubing sizes. 

For hose thread fittings (GHT; FHT; MHT), first check to see if a washer is present and next inspect to see if the washer is worn out.  A hose washer can be replaced if worn. (If it is hose thread). If the fitting is pipe thread (NPT; FPT; MPT), or you have confirmed the washers are present and in good condition it could be the structural integrity of the fitting has been compromised. Damaged threads may cause ill fitting connections that will leak. With other fitting types like insert fittings with barbs, you will want to assure the sizes are compatible with your tubing. The use of clamps is often the solution for a secure leakproof connection. Compression fittings (the tubing is pushed inside the opening of the fitting) are size specific for outside diameter of the tubing. Finally, you’ll want to check that the pressure in your system has not exceeded the operating pressure of the fittings, and that the fitting has not been subjected to constant pressure. Fittings are covered by our lifetime guarantee.


Some drippers have barbed inlets and outlets, which are commonly installed backwards. If you notice your drippers are not dripping, but leaking, around the connection to the tubing, try reinstalling the dripper the other way to see if this resolves the leak. For additional troubleshooting of drippers see Troubleshooting Drippers.

Connection to tubing: If the drippers are leaking from the connection in the tubing, make sure the dripper is pushed in all the way. If a punch was used that is not for drip irrigation or is dull the dripper may not seal correctly. Also if the dripper has been removed and replaced a few times the holes can stretch. You may have to punch a new hole and plug the leaky hole with a goof plug.