One of the more common calls we receive after a storm or power outage is:
“My HSTP won’t stop spraying. Is something wrong with it?”
In many cases, the answer is actually:
👉 No. Your system is doing exactly what it’s supposed to do.
While it’s normal for HSTP irrigation sprays to operate periodically throughout the day, there are certain situations where a system may appear to be spraying continuously.
The important thing to understand is that your HSTP is designed to remove excess treated water when water levels rise inside the system.
How Does a HSTP Know When to Spray?
Most HSTP systems use a submersible pump and float switch arrangement.
As treated water enters the pump chamber:
- the water level rises
- the float activates
- the submersible pump starts
- treated water is dispersed through the irrigation area
Once the water level drops:
👉 The pump switches off.
The system does not run on a timer.
It responds to water levels within the tank.
The Most Common Cause: Heavy Rain Events
One of the most common reasons a HSTP sprays more frequently than normal is heavy rainfall.
Although HSTP tanks are designed as sealed systems, extreme weather events can sometimes allow additional water to enter through:
- older pipework
- inspection points
- damaged infrastructure
- groundwater infiltration in older systems
When this occurs:
- water levels inside the system rise
- the pump activates more often
- irrigation sprays may appear to run continuously
In reality, the system is simply trying to remove excess water and return to normal operating levels.
If the Sprays Are Operating, That’s Usually a Good Sign
Many homeowners assume continuous spraying means the system has failed.
In fact, it often indicates the exact opposite.
If the sprays are operating:
👉 The submersible pump is working.
👉 The system is actively removing excess water.
👉 The system is attempting to return to normal operating levels.
Once the excess water has been pumped away:
👉 The spray cycles should return to normal.
Power Outages Can Cause the Same Thing
Another common scenario occurs after a power outage.
When the power is off:
- the aerator stops
- the submersible pump stops
- water continues entering the system from normal household use
As a result, water levels inside the tank can rise.
When power is restored:
👉 The submersible pump begins working again.
The system then starts pumping out the excess water that accumulated during the outage.
This often results in homeowners noticing the sprays operating far more frequently than normal.
Again, this is usually a sign that the system is catching up.
Blockages That Have Cleared
Sometimes a partial blockage can temporarily restrict wastewater movement.
Examples include:
- minor pipe restrictions
- debris around pumps
- temporary flow restrictions
When the restriction clears:
👉 The system suddenly has access to a larger volume of stored water.
The pump then works to remove that excess volume.
This can make it appear as though the system is spraying continuously.
Will the System Pump Itself Dry?
No.
This is a common misconception.
A HSTP is designed to maintain normal operating water levels.
The system will not continue pumping until the tank is empty.
Instead:
- the pump activates when water reaches a predetermined level
- the water level drops
- the float switch deactivates the pump
The tank always retains water as part of its normal operation.
If your system is spraying continuously, it’s usually because there is an increased volume of water above its normal operating level that needs to be removed.
When Should I Be Concerned?
You should consider contacting a service technician if:
- the alarm remains active
- the sprays continue operating for several days after rain has stopped
- water levels remain unusually high
- the irrigation area becomes excessively wet
- you notice unusual noises or odours
- the system does not appear to be recovering
These may indicate an underlying issue that requires investigation.
What About the Alarm?
Many HSTP systems are fitted with high-water alarms.
If excess water enters the system during:
- heavy rainfall
- stormwater ingress
- power outages
the alarm may activate.
As the submersible pump removes excess water:
👉 The alarm should eventually reset.
If the alarm remains active after conditions return to normal, further investigation may be required.
Why Regular Servicing Matters
Regular servicing helps identify issues before they become major problems.
During servicing, Maxfield’s Wastewater checks:
- submersible pump operation
- float switch performance
- alarm functionality
- irrigation performance
- overall system condition
This helps ensure your system is operating efficiently and responding correctly when unusual events occur.
We Carry Pumps and Parts on Every Service Vehicle
One of the biggest advantages of choosing Maxfield’s Wastewater is that we’re prepared.
Our service vehicles carry:
✔ Submersible pumps
✔ Aerator pumps
✔ Float switches
✔ Alarm components
✔ Common replacement parts
This means many issues can be diagnosed and repaired during the same visit, minimising downtime and inconvenience.
Speak with Jamie
If your HSTP is spraying continuously and you’re unsure whether it’s behaving normally or indicating a problem, we’re here to help.
At Maxfield’s Wastewater, we service and repair all major HSTP systems throughout the Moreton Bay region.
Contact Maxfield’s Wastewater and speak directly with Jamie.
Maxfield’s Wastewater
Local. Reliable. Done Right.
