Why Is Your Evaporative Cooler Leaking Inside? An Adelaide Plumber Explains
You walk past the ceiling vent and notice a damp patch spreading across the plaster. Or worse, water is actively dripping onto your floor. Your evaporative cooler is supposed to keep your home comfortable, not cause water damage.
Evaporative coolers use water constantly when running, with the sump holding over 12 litres at any time. When something goes wrong, that water can end up inside your home rather than evaporating through the pads as designed. The good news is that most leaks have straightforward causes, and catching them early prevents ceiling damage and expensive repairs.
Here are the five most common reasons your evaporative cooler might be leaking water inside, which ones you can check yourself, and when you need a plumber.
1. Float Valve Not Shutting Off Properly
The float valve works like the one in your toilet cistern. It controls the water level in the sump, shutting off the supply when the water reaches the right height. When this valve wears out, gets stuck, or sits at the wrong angle, water keeps flowing and eventually overflows.
A faulty float valve can cause leaking even when your cooler is switched off. If you notice water dripping hours after you turned the unit off, the float valve is often the culprit. The water level should sit about 15 to 20 millimetres below the overflow pipe. If the valve does not shut off at this level, it needs adjusting or replacing.
Can you fix it yourself?
You can check whether the float valve is the problem by turning off your water supply to the cooler and watching whether the leak stops. However, replacing or adjusting the valve itself requires climbing onto the roof and working safely around the unit. Most homeowners prefer leaving this to an experienced plumber.
2. Cooling Pad Deterioration and Mineral Buildup
Your cooling pads are supposed to absorb water evenly so the fan can draw air through them. When pads deteriorate or become clogged with mineral deposits, they stop absorbing water properly. Instead of soaking into the pad material, water can spray through gaps or pool unevenly, eventually finding its way into your ductwork.
Adelaide water makes this worse. With hardness levels around 97 to 111 mg/L, depending on your suburb, mineral deposits build up faster here than in cities with softer water. Northern suburbs like Salisbury and Elizabeth have the hardest water and tend to see pad problems develop more quickly.
Pads crusted with white calcium buildup cannot do their job. The fan motor can pull water droplets through damaged or poorly saturated pads, sending moisture directly into your ceiling space.
Can you fix it yourself?
You can visually inspect pads by removing the side panels of your unit. Look for white crusty buildup, tears, or sections that stay dry while the rest is wet. Replacing pads is a reasonable DIY job if you are comfortable on your roof, though many people prefer having a technician do it during a pre-summer service.
3. Water Distribution System Problems
Water reaches your pads through a network of small tubes and fittings inside the cooler. Over time, these distribution tubes clog with mineral deposits, especially in hard water areas. When tubes block partially, water pressure builds up and can spray in the wrong direction. Completely blocked tubes leave some pads dry while others flood.
Damaged water lines or loose fittings cause similar problems. Water that should flow to the pads instead leaks into the unit housing or directly into your ductwork. You might hear unusual sounds, like water spraying rather than the normal trickling, when distribution problems develop.
Can you fix it yourself?
Inspecting distribution tubes requires removing pads and accessing the internal plumbing of your cooler. While some homeowners tackle this, clearing blocked tubes and replacing damaged fittings is typically plumber territory. The job involves working with small components that are easy to damage if you are not familiar with the system.
4. Drain Valve Issues
Your evaporative cooler has a drain valve that releases water to prevent mineral concentration from building up too high. This bleed-off system should drain small amounts continuously or dump the sump periodically. When the drain valve fails, sticks, or clogs, water either backs up and overflows or drains excessively.
A blocked drain is particularly problematic. Water that cannot escape through the drain has nowhere to go except over the sides of the sump. This overflow often runs down onto your roof and finds its way inside through any available gap.
Can you fix it yourself?
Checking whether your drain valve is blocked or stuck requires roof access and familiarity with your specific cooler model. Replacing drain valves is straightforward work for a technician but fiddly for most homeowners.
5. Duct Condensation and Connection Problems
Sometimes the water is not coming from the cooler unit itself but is forming inside your ductwork. Cool air passing through ducts in a hot roof space can create condensation, especially if the ducts are poorly insulated or have gaps where warm attic air enters.
Loose duct connections cause a different problem. If the seal between your cooler and the dropper duct has deteriorated, water from the unit can run down the outside of the duct rather than staying contained. Damaged flashing around where the duct penetrates your ceiling also allows water entry.
Can you fix it yourself?
Duct problems require roof space access and proper sealing materials. If you see water stains tracking down the outside of your ductwork, or if condensation is forming on the duct surfaces, this needs professional attention to prevent ongoing damage.
Evap Cooler Leaking? Our plumbers service and repair all evaporative cooler brands across Adelaide. Same-day service available for urgent water damage situations. Call 0484 600 095 for a repair quote.
Why Pre-Summer Service Matters in Adelaide
Most evaporative cooler leaks reveal themselves on the first hot day after months of sitting idle. The cooler has been exposed to dust, debris, and possibly nesting insects through autumn and winter. Seals have dried out. Mineral deposits have hardened. Then you switch it on in late October and discover problems the hard way.
A pre-summer service in September or early October catches these issues before they cause water damage. The technician checks float valve operation, inspects and cleans pads, clears distribution tubes, tests the drain system, and examines duct connections. It costs far less than ceiling repairs.
Adelaide’s hard water also means your cooler works harder than units in softer water areas. Annual servicing removes the mineral buildup that accelerates wear on pumps, valves and pads. Homes in the northern suburbs should consider servicing even more frequently,y given the higher water hardness there.
What We Check During an Evap Cooler Service
When we service an evaporative cooler, we work through every component that can cause leaking. We test float valve operation and adjust or replace it if the water level is not correct. We examine pad condition, looking for mineral buildup, deterioration and uneven saturation. We clear distribution tubes and check fittings for damage.
We also inspect the water pump, drain valve and overflow system. We check duct connections for gaps or failed seals and examine the flashing where your unit meets the roof. If your cooler has been leaking, we trace the water path to identify exactly where it is entering your home.
After servicing, your cooler should run efficiently without sending water anywhere except through the pads and out as cool air.
Frequently Asked Questions
- Why is my evaporative cooler leaking when turned off?
A faulty float valve is the most common cause. If the valve does not shut off the water supply properly, the sump continues filling and eventually overflows. Turn off the water supply to your cooler at the tap and see if the leak stops. If it does, the float valve needs attention.
- Can hard water damage my evaporative cooler?
Yes. Adelaide’s moderately hard water leaves mineral deposits on pads, distribution tubes and pumps. This buildup reduces cooling efficiency and can lead to blockages that cause water to spray where it should not. Regular servicing removes buildup before it causes problems.
- How often should evaporative cooler pads be replaced?
Most pads last one to two cooling seasons in Adelaide, though this varies with water hardness and usage. Inspect pads before each summer. Replace them if they are heavily crusted with mineral deposits, torn, or no longer absorbing water evenly across their surface.
- Is water dripping from the duct normal?
No. Some moisture in the cooled air is normal, but visible dripping indicates a problem. This could be condensation from poorly insulated ducts, a leak from the unit running into the duct, or loose connections allowing water entry. Have it checked before water damage develops.
- Should I turn off the water when the cooler is not in use?
Yes, especially over winter. Turning off the water supply and draining the unit prevents standing water from causing corrosion and stops leaks if your float valve fails. This also reduces mineral buildup during the off-season.
- Can evaporative cooler leaks cause ceiling damage?
Absolutely. Water dripping onto ceiling plaster causes staining, sagging and eventually collapse if left untreated. Roof timbers can develop rot, and mould can grow in damp insulation. Address leaks promptly to avoid expensive repairs.
- How much does evaporative cooler repair cost in Adelaide?
Simple repairs like float valve replacement are relatively affordable. More complex work involving pump replacement, distribution system repairs or duct sealing costs more. A pre-summer service catching problems early is always cheaper than emergency repairs plus water damage restoration.
- When should I get my evaporative cooler serviced?
Book a service in September or early October before you need cooling. This gives time to order parts if anything needs replacing. Avoid the rush when the first heatwave hits and every technician in Adelaide is booked solid.
Stop the Leak Before It Causes Damage
Water inside your home from an evaporative cooler is not something to ignore. Whether it is a simple float valve adjustment or a more involved repair, fixing the problem early prevents ceiling damage, mould growth and larger repair bills down the track.
If you have noticed damp patches near ceiling vents, water stains spreading across your ceiling, or active dripping when your cooler runs, get it checked before summer hits in earnest.
Need your evaporative cooler repaired or serviced? Call Wills Plumbing on 0484 600 095 for prompt service across all Adelaide suburbs. We repair all brands and provide honest advice on whether repair or replacement makes more sense for your situation.
