Wet Patch After Rain? How to Tell If It’s a Hot Water Leak, Drainage Issue or Replacement Warning Sign
Wet patches around outdoor hot water systems are common after heavy rain across Brisbane, the Gold Coast and South East Queensland. Sometimes it is just rainwater sitting around a slab or low point. Other times, it can point to a leaking hot water tank, dripping valve, damaged pipework, blocked stormwater drain or poor drainage around the unit.
For homeowners, the hard part is knowing whether the water is harmless rainwater or a sign that the hot water system needs attention.
If the wet area dries once the weather clears, it may simply be surface water. But if the area stays wet, gets worse in dry weather, appears around the base of the cylinder, shows rust marks, sits near electrical areas or is linked with poor hot water recovery, it should be checked properly.
Hot Water Outlet sells supply-only hot water systems, heat pump hot water systems, electric hot water systems, gas hot water systems, instant gas hot water systems, solar hot water systems and valves, pipework and fittings. For installation, repairs, servicing, plumbing, gas fitting, drainage, leak detection or on-site fault finding, use a licensed trade such as JR Gas & Water.
Quick answer
A wet patch after rain near a hot water system can be caused by normal surface water, poor drainage, blocked stormwater, a leaking valve, damaged pipework, a leaking tank, a gas or electric hot water fault, or a solar/heat pump issue. Hot Water Outlet can help compare supply-only replacement systems and parts, but diagnosis, installation, repairs, gas work, electrical work, drainage and plumbing should be handled by licensed trades.
Why wet patches show up around hot water systems after rain
Outdoor hot water systems are usually positioned down the side of a home, near a wall, garden bed, fence, downpipe, slab, path or stormwater drain. These locations can work well, but they can also collect water after heavy rain.
A wet patch may appear because:
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Rainwater is sitting in a low area
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Stormwater is flowing toward the hot water system
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A nearby grate or strip drain is blocked
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A downpipe is discharging too close to the unit
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The concrete slab has poor fall
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Garden beds are holding water against the base
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A valve or fitting is dripping
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A storage tank is leaking
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Pipework has been damaged or corroded
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A heat pump drain path is poor
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A solar hot water tank or pipe connection is leaking
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A gas or electric unit is sitting in a poorly drained location
The wet patch itself is only a clue. The important part is working out whether it is rainwater, drainage, pipework or the hot water system.
When Hot Water Outlet can help
Hot Water Outlet is useful when the wet patch has revealed that an old or unreliable hot water system may need replacing.
This may include:
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An electric storage tank with rust or leaks
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A gas storage system showing corrosion around the base
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An instant gas system that is unreliable after storms
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A heat pump sitting in poor drainage or showing errors
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A solar hot water system that no longer recovers properly
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Valves, pipework or fittings that may need replacement
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A system that is too old, too small or no longer suitable for the household
Hot Water Outlet can help you compare supply-only:
Hot Water Outlet sells supply-only products and may help organise quotes from reputable installers where appropriate. It does not provide hot water repairs, plumbing repairs, drainage work, gas fitting or on-site service work.
When JR Gas & Water is the better next step
A wet patch is often a site issue, not just a product issue.
Use JR Gas & Water if you need help with:
If the water source is unclear, if the unit is leaking, if gas work is involved, if electrical parts may be affected, or if drainage is pushing water toward the system, arrange licensed help before ordering a replacement.
How to tell if it is just rainwater
A wet patch is more likely to be normal rainwater when:
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It appears only during or shortly after rain
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It slowly dries as the weather clears
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It sits in a low spot around the slab
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There is no rust staining
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There is no constant dripping from valves or pipework
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Hot water performance has not changed
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There are no error codes
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There is no gas smell
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The wet patch does not grow during dry weather
This does not always mean the location is ideal. If the same area floods after every storm, the drainage around the hot water system may still need attention.
Signs it may be poor drainage around the hot water system
Poor drainage is common around outdoor units, especially where hot water systems sit in narrow side access areas or near garden beds.
The wet patch may be drainage-related if you notice:
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Water flowing toward the unit
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Downpipes discharging near the base
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Mud or silt around the slab
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Leaves blocking nearby drains
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A strip drain or yard drain overflowing
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Water sitting for hours after rain stops
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Garden beds holding moisture against the unit
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Surface water moving toward the house
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The slab leaning or sitting in soft ground
Poor drainage can affect the area around the unit and may shorten the life of nearby components over time. If water keeps pooling, replacing the hot water system alone may not fix the real problem.
For stormwater and drainage work, use JR Gas & Water’s stormwater drainage solutions or drainage plumbing services.
Signs it may be a leaking hot water tank
A wet patch near a storage hot water system can be a warning sign if it continues after the rain has stopped.
The tank may be leaking if you notice:
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Water still appearing in dry weather
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Rust around the base of the cylinder
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Brown staining down the side of the tank
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A swollen or corroded base
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Water pooling directly under the tank
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Hot water running out faster than usual
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Inconsistent hot water recovery
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A system that has needed repeated repairs
A leaking storage cylinder is different from a minor valve drip. If the tank body has failed, replacement is often the practical option.
If the system is old or no longer suitable, compare supply-only electric hot water systems, gas hot water systems, heat pump hot water systems or general hot water systems.
Signs it may be a valve, pipework or fitting issue
Sometimes the wet patch is caused by a valve or pipe connection rather than the tank.
Look for visible signs such as:
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A valve dripping constantly
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Water marks below fittings
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Damp pipe joins
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Corroded fittings
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Damaged pipe insulation
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A relief drain running more than expected
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Water appearing from pipework after rain has stopped
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Pipework moved or damaged by debris
Hot Water Outlet stocks supply-only valves, pipework and fittings, but these parts need to be selected and installed correctly.
Do not modify pressure valves, relief valves, gas fittings, electrical components or hot water pipework yourself. Incorrect parts or installation can create safety, pressure and compliance issues.
For on-site valve, pipework or compliance work, book a licensed plumber.
Wet patch near an electric hot water system
Electric storage systems are common across Brisbane, the Gold Coast and SEQ. Many are installed outdoors on a slab, which makes wet patches easy to spot after rain.
Check from the outside for:
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Rust around the cylinder base
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Water pooling around the slab
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Leaks from visible fittings
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Poor hot water recovery
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Hot water running out faster than usual
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Water near conduit or electrical areas
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A tripped circuit
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A tank that appears to be leaning
Do not remove covers or keep resetting a system that keeps tripping. Electrical work should always be completed by a licensed electrician.
If the unit is old, rusty, leaking or no longer suitable, compare supply-only electric hot water systems. You may also want to compare heat pump options if the home has suitable outdoor space, airflow and drainage.
Wet patch near a heat pump hot water system
Heat pump hot water systems need suitable airflow, drainage and outdoor placement. A wet patch around the base can be a sign of poor drainage, blocked airflow, normal condensate, or another issue that needs checking.
Look for:
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Water pooling around the unit
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Mud around the base
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Leaves blocking the fan area
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Error codes
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Slower hot water recovery
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Unusual noise
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The unit sitting too close to walls or fences
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Water draining somewhere unusual
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Debris packed around the system
Heat pumps can reduce running costs compared with standard electric storage when selected and installed correctly, but the home and site need to suit the system. Outdoor space, airflow, drainage, noise location and household demand all matter.
If your existing unit is due for replacement, compare supply-only heat pump hot water systems.
Wet patch near a gas hot water system
Gas hot water systems need safe ventilation, correct installation and licensed gas fitting. A wet patch near a gas unit should be checked carefully, especially if there are smells, error codes or reliability issues.
Warning signs include:
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Gas smell near the unit
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Error codes
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Hot water cutting in and out
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Ignition problems
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Water sitting around the base
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Debris around ventilation areas
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Soot marks
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Unusual noises
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Poor hot water delivery
Gas work should always be completed by a licensed gas fitter. Do not open the unit, adjust gas components or continue using a system that appears unsafe.
If the system is old or unreliable, compare supply-only gas hot water systems and instant gas hot water systems. For gas fitting or on-site diagnosis, use JR Gas & Water.
Wet patch near a solar hot water system
Solar hot water systems can involve roof-mounted collectors, outdoor tanks, valves, pipework and boosters. A wet patch near the tank may be connected to the ground-level system, pipework, valves or drainage.
From the ground, check for:
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Water around the storage tank
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Visible pipework leaks
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Rust around fittings
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Poor hot water recovery
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Booster issues
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Watermarks near the tank
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Dampness around visible pipework
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Leaks that continue after rain stops
Do not climb onto the roof, open components or attempt to repair solar hot water pipework yourself. Roof work, plumbing and electrical work should be completed by licensed trades.
If the system is old or no longer suitable, compare supply-only solar hot water systems, or compare solar against heat pump, electric or gas replacement options.
What homeowners can safely check
You can do a few safe checks before deciding what to do next.
Check:
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Whether the wet patch dries after rain stops
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Whether water is flowing toward the unit
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Whether downpipes are discharging nearby
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Whether leaves are blocking a nearby drain
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Whether there is rust around the tank
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Whether valves or fittings are dripping
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Whether hot water performance has changed
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Whether there are error codes
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Whether there is a gas smell
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Whether water is near electrical areas
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Whether the same patch appears in dry weather
Avoid unsafe work such as:
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Removing hot water system covers
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Touching wiring or electrical controls
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Adjusting gas components
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Modifying valves
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Disconnecting pipework
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Opening pressurised plumbing
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Digging near unknown services
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Standing in floodwater
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Continuing to use a system that appears unsafe
Photos can help a licensed trade or product support team understand what is happening, especially if the area dries before someone attends.
Should you replace the system or fix the site issue first?
The right answer depends on what is actually causing the wet patch.
A replacement system may make sense when:
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The tank is leaking
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Rust is advanced
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The unit is old and unreliable
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Hot water recovery is poor
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Repairs are becoming frequent
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The system is too small for the household
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The current system is no longer suitable
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You want to compare more suitable product options
Licensed site work may be needed first when:
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Stormwater is flowing toward the unit
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The slab is unstable
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Drainage is blocked
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Pipework is leaking
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A valve issue needs diagnosis
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Gas fitting is required
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Electrical work is required
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The same wet patch returns after every storm
Hot Water Outlet is best for comparing supply-only replacement products. JR Gas & Water is the better option for installation, repairs, servicing, leak detection, plumbing, gas fitting and drainage work.
Brisbane, Gold Coast and SEQ context
Wet patches around outdoor hot water systems are common across South East Queensland because homes vary widely in age, layout and site conditions.
Brisbane homes may deal with older electric storage systems, clay soil, narrow side access, high water pressure, older stormwater layouts and established tree roots.
Gold Coast homes may deal with flatter blocks, coastal corrosion, exposed outdoor units, duplex access and stormwater load.
Acreage and outer SEQ homes may involve LPG, sheds, long pipe runs, larger roof areas, rainwater tanks and more complex outdoor plumbing.
Townhouses and body corporate properties can also be more complex because drainage, access and shared pipework may limit where a new system can go.
That is why the right hot water system should be matched to the home, not just selected by price.
Replacement options to compare
Heat pump hot water
A heat pump can reduce running costs compared with standard electric storage when selected and installed correctly. It can suit many SEQ homes with suitable outdoor airflow, space and drainage.
Compare supply-only heat pump hot water systems if you are considering moving away from standard electric storage.
Electric storage hot water
Electric storage remains a familiar option for many homes, especially where the existing setup is simple and the household wants a conventional storage replacement.
Compare supply-only electric hot water systems if you want a straightforward replacement type.
Gas storage hot water
Gas storage can suit some homes with existing gas infrastructure and suitable outdoor placement.
Compare supply-only gas hot water systems if the home already uses gas and the site is suitable.
Instant gas hot water
Instant gas systems can suit homes wanting continuous flow hot water, but gas supply, sizing, water demand and installation requirements matter.
Compare supply-only instant gas hot water systems if you are considering changing from storage to continuous flow.
Solar hot water
Solar hot water can suit selected homes with the right roof, orientation, household demand and installation conditions.
Compare supply-only solar hot water systems if you are replacing an existing solar setup or comparing solar against heat pump, electric or gas options.
FAQs
Is a wet patch near my hot water system always a leak?
No. It may be rainwater, poor drainage, stormwater overflow, normal surface water or a leaking hot water component. If the wet patch remains after the rain stops, appears in dry weather, shows rust stains or sits directly under the unit, it should be checked.
How do I know if my hot water tank is leaking?
A leaking tank may show water around the base after the area has dried, rust marks, brown staining, a corroded base or ongoing water pooling. If the cylinder itself is leaking, replacement is often more practical than repair.
Can poor drainage damage a hot water system?
Poor drainage can contribute to corrosion, unstable bases and ongoing moisture around the system. It can also hide leaks and make servicing harder. If water regularly pools around the unit, the drainage should be assessed before replacing the system.
Can I replace my electric hot water system with a heat pump?
You may be able to, but suitability depends on outdoor space, airflow, drainage, household demand, noise location and installation requirements. Compare heat pump hot water systems and arrange licensed advice where site conditions are unclear.
What should I do if I smell gas near my hot water system?
Do not ignore it. Avoid ignition sources, turn off the appliance if safe to do so, leave the area and arrange help from a licensed gas fitter. Gas work should always be completed by a licensed gas fitter.
Does Hot Water Outlet install hot water systems?
Hot Water Outlet sells supply-only hot water systems and related products. For installation, repairs, servicing, plumbing, gas fitting, drainage or on-site work, use a licensed trade such as JR Gas & Water.
Can I buy valves and fittings through Hot Water Outlet?
Yes. Hot Water Outlet stocks supply-only valves, pipework and fittings. These products should be selected and installed correctly by licensed trades where plumbing work is required.
Should I order a replacement hot water system before fixing drainage?
Not if drainage is the real issue. If stormwater is repeatedly flowing toward the unit or pooling around the base, the drainage problem should be considered before putting a new system in the same location.
Need to compare supply-only hot water systems after finding a wet patch?
If a wet patch after rain has exposed an old, rusty, leaking or unreliable hot water system, Hot Water Outlet can help you compare supply-only hot water systems, including heat pump, electric, gas, instant gas and solar options.
For installation, hot water repairs, servicing, leak detection, burst pipes, stormwater, drainage, gas fitting or on-site plumbing work, book JR Gas & Water through the quote request and bookings page.
