Most Sanur villas rely on a rooftop tank fed by PDAM mains or a well pump. Left unattended for several months, that tank becomes a home for algae, iron sediment, and biofilm – especially in the humid coastal air. Here is what to check, how often to do it, and when it is time to call a technician instead of DIY-ing it yourself.
Why Your Villa Needs a Rooftop Tank
PDAM pressure in Sanur can be fine one morning and barely a trickle the next, particularly during the dry season when demand spikes across the peninsula. A rooftop tank (often called a tandon locally) acts as a buffer so your showers, kitchen tap, and pool top-up keep running even when the supply dips.
If you draw from a private well, the situation is different: the pump pushes water up at a fixed rate, and without storage you either run the pump continuously or go dry. The tank also protects the pump from short-cycling, which saves electricity and extends motor life.
One Sanur-specific note: salt-laden sea air accelerates corrosion on metal fittings around the tank inlet and overflow pipe. If your villa was built before 2010, those connections are worth inspecting every year.
How Often Should You Clean It?
As a practical rule: open and clean the tank at least twice a year – once before the rainy season (around October) and once after it (around May). Rainy-season runoff washes leaves, bird droppings, and dust into the manhole opening, and that organic matter starts growing within two or three weeks in Bali's humidity.
Well-fed tanks tend to need more frequent attention because iron and fine silt settle on the bottom. If you see a rusty tint in the first glass of water each morning, schedule a cleaning sooner rather than later.
If your tank looks like it needs more than a brush-and-rinse job, send me a photo of the manhole area and the float valve on WhatsApp and I will tell you exactly what to expect before we schedule a visit.
Step-by-Step: Cleaning the Tank Yourself
You do not need special tools for a basic service, but do wear rubber gloves and work early in the morning when the water is coolest. Here is the sequence I recommend:
If the tank feeds a chlorine-based pool system, never mix residual chlorine with any acid-based cleaner inside the tank. Stop, ventilate, and call a professional if you are unsure what chemicals have been used nearby.
- Shut off the well pump or close the PDAM inlet valve so no new water enters the tank.
- Open the drain cock at the base (or uncap the overflow) and let the tank empty completely into a bucket or garden hose run – do not pour onto electrical outlets or the pump junction box.
- Climb up safely (use a proper ladder, not stacked chairs), open the manhole lid, and scrape visible algae, sediment, or biofilm with a stiff nylon brush. Avoid steel wool; it scratches plastic and leaves rust particles behind.
- Rinse thoroughly with clean water from a separate source until the runoff runs clear.
- Optional disinfection: add a small amount of food-grade sodium hypochlorite (the same type used to top up pools) at the dilution printed on the bottle, let it sit 30 minutes, then rinse again. Do NOT combine this with vinegar, citric acid, or any other acid product in the same pass.
- Refill slowly, watch for leaks around the inlet gasket and overflow pipe, and close the manhole lid tightly.
The Float Valve: Small Part, Big Headache
Inside most plastic tandon tanks there is a float valve (sometimes called a ballcock) that shuts off the inflow when the tank reaches capacity. When it sticks or the float develops a hairline crack, the tank overflows continuously – you may notice a wet patch under the roof edge or a sudden jump in your PDAM bill.
Test it simply: fill the tank, then wait ten minutes. If water is still trickling into the tank after it looks full, the valve is not seating properly. A quick fix is often just cleaning mineral scale off the rubber seat; if the float itself is swollen or cracked, replace the whole assembly. The part is inexpensive, but fitting it correctly on a rooftop in the heat is fiddly work many owners prefer to hand to a technician.
When Is It Time to Replace the Tank?
Plastic tanks in Bali typically last 10–15 years before UV exposure and thermal cycling make the walls brittle. Warning signs include visible cracks near the base, a persistent musty smell that no amount of scrubbing removes, or a permanent yellow-brown film on the interior surface.
Older villas sometimes had metal or fibre-glass tanks installed in the 90s. Those are more prone to internal rust and are harder to clean thoroughly. If you are already replacing the float valve and the tank body feels soft or discoloured, it usually makes sense to swap the whole unit while you have scaffolding up.
A new tank also gives you the chance to add an overflow pipe that routes excess water into your garden irrigation rather than letting it cascade down the wall and erode the plaster – a common sight on older Sanur properties after a heavy monsoon week.
Questions
Can I use bleach from the supermarket to disinfect the tank?
Use only food-grade sodium hypochlorite at the dilution stated on the label, rinse well, and never mix it with acid-based products. If you are unsure what is already in the system (pool chemicals, for example), stop and call a technician before adding anything.
My PDAM water tastes slightly metallic. Is the tank the cause?
It can be. Iron sediment from the mains or from corroded inlet fittings settles in the tank and re-dissolves over time. A thorough clean plus checking the inlet gasket often solves it; if the taste persists, the issue may be upstream in the PDAM line or in old copper/steel pipes inside the villa.
Do I need to turn off electricity before cleaning?
Yes. Switch off the well pump breaker and any immersion heater that draws from the same circuit. Water and live electrics near the rooftop junction box are a genuine shock hazard – do not work around wet outlets without confirming they are de-energised.
I'll reply with what's needed, a price and when I can come.
