Common Causes of Low Sprinkler Water Pressure and How to Fix Them in San Antonio, TX

In San Antonio, TX, homeowners depend on their sprinkler systems to keep lawns healthy despite the intense South Texas heat. One of the most frequent problems these systems face is low water pressure, which leads to weak spray, uneven coverage, or dry patches across the yard. If not addressed promptly, low pressure can damage landscaping and increase water bills.

Andy’s Sprinkler, Drainage, & Lighting proudly serves San Antonio and also provides expert sprinkler repair in Carrollton, Southlake, Austin, and Lubbock. Our licensed professionals understand the challenges of Texas irrigation systems and know how to restore proper water pressure to keep your landscape thriving year-round.

In this post, we’ll discuss some of the common reasons for low pressure sprinklers.

How Water Pressure Works in Sprinkler Systems

Water pressure in irrigation systems is measured in PSI (pounds per square inch). Spray heads usually work best between 15–30 PSI, rotors require 30–50 PSI, and drip irrigation systems function around 10–25 PSI.

For San Antonio homeowners, this balance is especially important. With long, hot summers and limited rainfall, sprinkler systems often run heavily. If PSI isn’t properly maintained, lawns may develop dry spots or waste water through misting. Adequate water pressure ensures even coverage and helps conserve water, which is especially critical in this region.

Table of Contents

Causes of Low Sprinkler Pressure
Troubleshooting Low Pressure
Fixes and Upgrades
Preventive Maintenance

Backflow Preventer Valve Issue

One of the leading reasons for low sprinkler water pressure relates to the valves on your backflow preventer device. If you notice limited water pressure in your sprinkler system but normal water pressure inside your home, then the problem might be that your backflow preventer valves are not completely open.

If this is the only issue, the fix is simple: access your backflow valves and open them completely to improve your water pressure. Most backflow preventer devices have two pipes: one horizontal and one vertical. Since there is typically a valve on both pipes, make sure they are fully open.

The valves are considered open once they are parallel to the pipe. It’s recommended to adjust the horizontal pipe first, then the vertical. To ensure it’s done correctly, and to verify this is the only cause, it’s best to call a professional.

Water Line Leak or Break

A more concerning issue is a water line leak or break. This can happen when digging in the yard and accidentally hitting a pipe, or when San Antonio’s clay soil shifts after rain and drought cycles.

Signs of a leak include depressions in your yard, soggy areas, bubbling water, or sprinkler heads that stop working in sequence. If this happens, it’s important to call a sprinkler repair technician quickly to prevent further damage and water waste.

Shut-Off or Main Water Valves Aren’t Fully Open

Your sprinkler system depends on valves being fully open. This includes the dedicated shut-off valve for the sprinkler system and the main water valve that serves the entire home. If either one isn’t completely open, you’ll notice low pressure across all zones.

A professional can help locate these valves, confirm they are open, and ensure the system is pressurized correctly.

Clogged or Dirty Sprinkler Heads

Sometimes the problem isn’t water supply—it’s the sprinkler heads themselves. Dirt, grass clippings, and hard water sediment are common culprits in San Antonio.

You may notice some heads spraying normally while others are weak. Cleaning or replacing these heads often resolves the issue. Because proper disassembly and cleaning require care, scheduling a professional cleaning service is recommended.

Water Line Obstruction

Underground obstructions also cause low pressure. Tree roots from San Antonio’s common oaks, pecans, and mesquites can wrap around pipes or infiltrate them over time. This reduces water flow and can damage your irrigation system.

If you suspect root intrusion or pipe blockage, professional inspection is necessary to locate and resolve the problem.

Other Common Causes of Low Sprinkler Pressure

Additional causes include:
• Too many sprinkler heads per zone, creating overload.
• Undersized or older pipes restricting flow.
• Municipal water pressure drops during peak summer demand.
• Zone valve or timer malfunction.
• Whole-home filtration or softeners restricting water flow.

How to Test for Low Water Pressure

Before calling for repairs, try these quick checks:
• Attach a pressure gauge to an outdoor faucet (15–30 PSI for spray heads, 30–50 PSI for rotors).
• Check your water meter for movement that may indicate leaks.
• Perform a bucket test by timing how long it takes to fill a gallon container.
• Observe spray patterns for gaps or weak coverage.

These tests provide valuable clues to share with your sprinkler technician.

Fixes and Upgrades

Solutions may include:
• Cleaning or replacing nozzles.
• Repairing small leaks.
• Splitting overloaded zones for better flow.
• Installing a booster pump to handle low city water supply.
• Replacing undersized or corroded piping in older systems.
• Switching to low-flow or rotary nozzles for better efficiency.

Preventive Maintenance Tips

To prevent low pressure issues:
• Flush the system every season.
• Clean heads and filters regularly.
• Inspect valves and lines annually.
• Winterize your system before San Antonio’s occasional freezing nights.
• Upgrade to smart controllers for better scheduling and water savings.

Choose Andy’s Sprinkler, Drainage, & Lighting Today!

If you’re dealing with any of the issues outlined above, then it’s time to pick up the phone and call Andy’s Sprinkler, Drainage, & Lighting, find out which location offers sprinkler repair near you. We offer top-notch sprinkler system services and we can ensure your yard is ready to look its best! Contact us today to schedule an appointment.