How can I get low water pressure in sprinkler system fixed?

Question

I have a new house that is still under warranty. Compared to at least two of my neighbors whose houses were built by the same builder and have very similar sprinkler systems, my sprinklers put out very low water pressure. The water pressure is so low that several sprinklers don't even deploy (that is they don't fully come out of the ground).

I demonstrated the problem to the builder, and he's sent out two different contractors in succession (first was a sprinkler guy, then was a plumber) that have said that it's not their area of expertise. The plumber confirmed that the decrease in water pressure was localized to the sprinkler system (water pressure at the exterior spigots was 55 psi, I believe), which I already knew from anecdotal experience, and said that an irrigation specialist would be the one to call.

Given the way the last two experiences have turned out, I'm hesitant to tell the builder to call a third contractor before I have a better understanding of the steps needed to get this problem solved, because to this point I've just had to take what the contractor's have said at face value.

So here are some specifics I would like to know:

1. Is it likely that the plumber is right, that the problem will necessitate an irrigation specialist (by process of elimination, I would expect this is true, but I had no idea of the existence of such a specialist before the plumber mentioned it)?
2. Are there any steps that I can take to better prepare for the next contractor?
3. Is there information that I'm missing that I should try to collect? I've basically given all of this information to the builder and the contractors, but we still haven't arrived at a solution.
4. Neither of the two contractors spent more than a couple minutes trying to diagnose the problem. Once I'm pretty sure I have the right sort of contractor, is there anything I can do to make sure that the he or she actually works to pinpoint the precise problem before trying to pass me along to someone else?

Notes:

• I haven't noticed any water pooling in my yard, so if there's a leak in the irrigation system, it's not obvious where it is, but my yard is pitched pretty sharply for drainage purposes, so I don't think that this indicates that there is no leak.
• Water pressure in the house is quite good
• At each step, I've actually had to push to get everyone to acknowledge that the problem isn't just that the city is not supplying my house with enough water pressure, which considering all the above, indicates to me that this is the sort of problem that nobody wants to deal with, probably because it's difficult and time consuming.
• The sprinkler system is separated into zones, one of which only has two sprinklers, so I think that it's unlikely that the system simply has too many continuously running sprinklers to maintain enough water pressure.

Answer 1

Clogged line

There could be a clog in the lines feeding some of the sprinklers, or clogged up sprinkler heads.

• Remove all the sprinkler heads (the procedure will vary based on the type of heads).
• Inspect and clean the heads.
• Turn the system on.

If you don't notice any dirt or gunk coming out, and the pressure does not increase in the low flowing outlets. Cap the working outlets, and turn the system back on. If you still don't notice a difference, you might have to dig up the lines to inspect them.

Damaged line

The line feeding some of the sprinklers could have been crushed, damaged, or broken.

• Cap the working sprinklers.
• Turn the system on.

If the pressure in the low flow heads does not increase, you'll likely have to dig up the lines and inspect them.

Not enough pressure

It could just be that the system does not have enough pressure for all the heads to work simultaneously.

• Cap one of the working sprinklers.
• Turn on the system.
• Repeat.

If each time you cap an outlet you notice the pressure increase in the low flow heads, it could be that there is just not enough pressure to operate all the heads at once. In this case you might have to have the system split into zones, and only run one zone at a time.

Answer 2

The first thing Shawn said was "new house that is still under warranty". So all these detailed debugging suggestions are really beside the point. The builder is the GENERAL contractor. That means HE should be figuring out which subcontractor to send out to analyze the system and talking to them to get their report and deciding what to do next. Shawn should not have to do any of this. The GC has the general responsibility.

It may be useful to report to anyone involved that water pressure at the exterior spigots was tested and measured at 55 psi but even that is not really Shawn's responsibility.

As far as escalation, most states license contractors so you could certainly put some pressure on that way if you wish.

Of course I have to talk about debugging too. Accessibility is limited with sprinkler systems but the valves are usually above ground or in a valve box. They may have some maintenance features to help you get an idea of what the water pressure in that part of the system is.

There is also a feature called a "flow control" on the better valves. If that is not adjusted correctly it could easily cause your symptoms.

Another possibility is if your system has a filter, it might be clogged with debris from construction. They are usually easy to clean.

If you want more details, please give us more details like valve model #, whether you have a filter, etc. But really, your builder should honor his warranty. If not, there should be plenty of ways to get his attention.