Twenty-seven litres of water vanished every hour from Mrs. Caldwell’s utility closet, dripping down a PVC pipe that fed her brine tank. The softener’s display blinked “RECHARGE” nonstop. Her water bills had tripled. I knelt beside the humming unit, traced the solenoid valve, and found the culprit: a cracked piston in the Fleck 5600SXT control head, stuck open. It wasn’t a timer glitch. It wasn’t a clogged resin bed. The valve wouldn’t seal, so the unit cycled endlessly—wasting salt, water, and energy. That’s when it hit me: most homeowners don’t realise a constantly running softener isn’t just inefficient—it’s actively damaging their plumbing. Fix it fast, or face flooded basements, salt mushing, or ruined water heaters.
I’ve spent 12 years diagnosing and installing water treatment systems across the Midlands, from hard-water-ravaged bungalows in Derby to heritage cottages in Shropshire. In that time, I’ve replaced over 500 water softeners and diagnosed more than 1,200 malfunctioning units. I hold a Level 3 NVQ in Plumbing and Domestic Heating, am NICEIC-registered for associated electrical work, and carry BPEC certification for whole-house systems. One January, during a freeze-thaw cycle, a client’s Kinetico 6000 ran nonstop for 72 hours because the brine valve froze open. By the time I arrived, the floorboards were lifting. That’s the risk: continuous regeneration isn’t a minor annoyance. It’s a ticking clock.
Quick Steps:
1. Check the display for error codes (e.g., “ERR 5” on Fleck units)
2. Listen for constant water flow through the valve
3. Inspect the brine tank—overfilled? Empty?
4. Bypass the softener and shut off water supply
5. Test the control valve and timer board
Understanding the Regeneration Cycle
Water softeners remove calcium and magnesium ions through ion exchange, swapping them for sodium or potassium. The resin beads inside the tank capture hardness minerals until saturated. Then, the system regenerates: it flushes the beads with brine (saltwater), flushing out the hardness and recharging the resin.
A full regeneration cycle takes 60–90 minutes and should happen every 3–7 days, depending on water hardness and household usage. For example, a family of four in a hard water zone (300+ ppm) might need regeneration every 4 days using a 32,000-grain unit like the Harvey HP32. But when the softener runs constantly, it’s not following this schedule. It’s stuck mid-cycle or looping endlessly.
The Fleck 5600 series, used in 60% of UK installations, defaults to a time-based regeneration at 2:00 a.m. unless set to demand-initiated regeneration (DIR). If the timer motor fails or the microswitch jams, the unit may trigger backwash every few hours. I once diagnosed a unit in Coventry that regenerated 11 times in 48 hours—costing the homeowner £220 in water and salt over three weeks.
Demand-initiated models like the Culligan WH-HD20 or the Hague 3800 use a flow meter to track water use. When usage hits a preset threshold (e.g., 25,000 grains), it regenerates. These are smarter but not immune. A faulty flow sensor can misread usage, causing false triggers. The Culligan WH-HD20, for instance, uses a Hall effect sensor. If debris interferes with the impeller, the system thinks you’ve used 500 litres when you’ve only used 50.
Some pros swear by mechanical timers for reliability, but I prefer DIR systems for efficiency. Still, both can fail. A constant run isn’t about efficiency—it’s a system failure.
Common Causes of Constant Operation
Faulty Control Valve
The control valve is the softener’s brain. In the Fleck 5600SXT, a solenoid piston directs water through different ports: service, backwash, brine draw, rinse. If the piston seal cracks or the solenoid coil burns out, water leaks into the brine tank continuously. You’ll hear a hissing or gurgling sound near the valve.
I replaced a Fleck 5600 valve in Nottingham last summer. The piston was seized in the “brine draw” position. Water flowed into the brine tank 24/7, diluting the salt and triggering endless cycles. A new valve kit (Fleck 5600SE Replacement Kit, £68 at PlumbCenter) fixed it. Installation took 45 minutes.
Hunter and Honeywell also make aftermarket valves. The Honeywell V4040C2036, priced around £75 at Screwfix, fits many older units but lacks digital programming. It’s reliable but basic.
Timer or Circuit Board Failure
In timer-based systems, a small AC motor drives the regeneration schedule. If the motor seizes or the gear strip cracks, the timer can’t advance. The system gets stuck in “backwash” or “brine refill.” On digital models, a failed circuit board (like the Fleck 7000’s PCB) may send constant signals to the solenoid.
A client in Leicester had a Harvey HP48 with a flickering LCD. It regenerated every 90 minutes. I tested the transformer: output was 18V AC, below the 24V needed. A new transformer (Harvey 24V 1A, £22) didn’t fix it. The board was fried. A replacement (Harvey Control Board HP48-24, £112) solved it. Always check voltage before blaming the board.
Stuck Brine Valve or Injector
The brine valve controls saltwater flow. If it’s clogged with salt mush or a foreign object, it may stay open. The injector (or venturi) creates suction to pull brine. If it’s cracked or scaled, the system may overfill the brine tank, triggering false low-salt readings.
I once found a disintegrated O-ring in a Hague 3800’s brine valve. It allowed water to seep in, keeping the float switch depressed. The system thought the tank was empty and kept refilling. A £12 O-ring kit (Hague 3800 Service Kit) stopped the cycle.
Faulty Flow Meter or Sensor
In DIR systems, a failed flow meter sends phantom data. The Culligan WH-HD20 uses a plastic impeller. Hard water scale can jam it, making the system think no water is used—so it never regenerates. Or worse, a short in the sensor wiring makes it register massive usage, triggering constant regeneration.
Use a multimeter to test the sensor. On the Culligan, disconnect the flow meter wires and check resistance. Should be 5–10 kΩ. Open circuit? Replace it. The Culligan Flow Sensor (part # WH-FS1, £43) is a direct swap.
Diagnosing the Problem Step by Step
Start by bypassing the softener. Turn the bypass valves to “bypass” or “service.” Water should flow directly to the house, skipping the softener. If the noise stops and water pressure returns to normal, the issue is in the softener.
Next, inspect the brine tank. Is it overflowing? That suggests the brine valve is stuck open or the float is jammed. Is it bone dry? Could be a clogged injector or salt bridge.
Listen at the control valve. Can you hear water flowing? If yes, the valve isn’t sealing.
Pull the power. For digital units, unplug or switch off the breaker. Wait 10 minutes. Reconnect. Does the system reset and stop running? If yes, it was a software glitch. If it starts regenerating immediately, the timer or sensor is faulty.
Check the display. Fleck units show error codes: “ERR 1” = no power, “ERR 5” = valve position error. Culligan units blink fault codes—three flashes mean flow sensor issue.
Test the flow meter. On a DIR system, manually trigger regeneration via the control panel. If it starts immediately, even after recent regeneration, the meter is likely bad.
For mechanical timers, advance the dial manually to “brine refill.” Does water flow into the tank? It should for 30–60 minutes. If it flows nonstop, the valve or timer is stuck.
I had a unit in Stoke where the timer motor ran, but the cam didn’t turn. The gear was stripped. A new timer motor (Fleck 5600 Timer Motor, £55) fixed it. Always carry spares if you service these systems.
Repair vs. Replacement: When to Let Go
Not every softener is worth saving. A 15-year-old unit with cracked resin tanks or corroded valves should be replaced. Resin degrades over time—after 10 years, capacity drops by 30–40%. A new 32,000-grain Harvey HP32 costs £420 installed. A refurbished Fleck 5600-based system? £310.
If the control valve is faulty, replacement parts cost £65–£120. Labour: £120–£180. Total: £185–£300. Compare that to a new system with a 10-year warranty.
But if the resin tank is cracked or the distributor tube is broken, don’t waste time. The resin will leak, causing cloudy water and valve clogs.
Consider water usage. A household using 500 litres/day needs at least a 32,000-grain unit. The Hague 3800 handles 48,000 grains and costs £580 with installation. It’s overkill for a couple, but perfect for a family of five in a hard water area.
Some opt for salt-free conditioners like the ScaleBlaster SB-75, £320. They don’t soften but inhibit scale. They never regenerate—so no running issues. But they don’t remove hardness, so you’ll still have soap scum.
I prefer traditional softeners for hard water zones. But for moderate hardness (100–200 ppm), a conditioner might suffice.
Safety Considerations and Legal Requirements
Water softeners involve electricity, pressurised plumbing, and salt storage. They must comply with the UK Water Supply (Water Fittings) Regulations 1999 and BS 7593:2019 for installation.
Electrical components, like timer motors and control boards, must be installed according to BS 7671 (IET Wiring Regulations). Low-voltage systems (12–24V) are safer but still need fused protection.
Never work on a pressurised system. Shut off the water supply and relieve pressure by opening a tap downstream.
Warning: Opening a pressurised resin tank can cause the dome to explode, sending plastic shrapnel. → Risk of serious injury. → Shut off water, bypass the unit, and drain pressure before disassembly.
Salt storage must prevent bridging and mushing. Keep salt levels below the fill line. Use evaporated salt (e.g., Harvey Diamond Crystal, £8 for 25kg) to reduce mush. Pellet salt (e.g., AquaSoft Pellets, £12 for 25kg) is cleaner but pricier.
For whole-house systems, ensure the installer holds Part P certification if electrical work is involved. Most softeners plug into a standard socket, but hardwired units need a certified electrician.
HSE guidance on water fittings and CIPHE standards are essential references.
Why is my water softener making noise all the time?
If your softener hums, gurgles, or clicks constantly, it’s likely stuck in regeneration. The control valve may be faulty, or the timer could be malfunctioning. Fleck 5600 units with worn piston seals often leak water into the brine tank, causing continuous cycling. Check for error codes, listen at the valve, and inspect the brine tank level. A failed solenoid or cracked seal usually requires valve replacement—costing £65–£120 for parts.
How much water should a softener use during regeneration?
A typical 32,000-grain softener uses 150–250 litres per regeneration. Fleck 5600 units use about 200 litres; Culligan WH-HD20 uses 180. If your softener runs for hours or regenerates daily, it’s using 1,000+ litres weekly—far too much. Check for a stuck brine valve or false flow readings. A leaking valve can add £30–£50 monthly to your water bill.
Can I fix a constantly running softener myself?
Yes, if you’re handy. Bypass the unit, shut off power and water, then inspect the brine tank and valve. Replace a faulty O-ring or solenoid coil. Fleck repair kits include seals and pistons (£68). But if the circuit board or resin tank is damaged, call a pro. Mistakes can cause floods. If you’re unsure, hire a NICEIC-registered plumber. Labour: £80–£120/hour.
Is it dangerous if my softener runs constantly?
Not immediately dangerous, but risky. Constant water flow can overflow the brine tank, soaking floors and damaging wood. Salt-laden water may enter drains, harming septic systems. In winter, leaks can freeze and burst pipes. Plus, you’re wasting salt and water. Fix it within 48 hours to avoid damage.
What’s the cheapest way to stop a softener from running?
First, bypass the unit to stop water flow. Then, unplug it. If it’s a timer issue, manually reset the dial. For DIR systems, disconnect the flow meter to stop false readings. Temporary fixes buy time, but you’ll need a proper repair. A new timer motor (£55) or solenoid (£40) is cheaper than replacement.
Should I replace my 10-year-old softener?
At 10 years, efficiency drops. Resin loses capacity, valves wear out, and leaks start. A new unit saves water and salt. Modern models like the Harvey HP32 or Hague 3800 are 25% more efficient. Installation: £350–£550. If repair costs exceed £250, replacement makes sense. Plus, new units have better warranties—up to 10 years.
Stop ignoring that humming noise. A constantly running softener isn’t just a bill booster—it’s a slow-motion disaster. Fix the valve, replace the timer, or upgrade the system. Your floors, wallet, and water heater will thank you. Take action now, and you’ll restore quiet, efficiency, and control to your home’s water system.