Short answer: the physical mounting you can probably do yourself. The electrical connection you shouldn't. Here's why.
The electrical connection. A water heater draws 1,500W–4,000W continuously. This requires a dedicated circuit from the MCB panel with correctly sized cable (minimum 2.5mm² for most heaters). Installing this yourself without knowing the existing circuit layout in your Bali villa is risky — you need to know what MCB to use, whether there's capacity in the panel, and whether existing wiring on the circuit can handle the load.
Many Bali villas have non-standard wiring — cables that aren't the colour they should be, undersized wiring that's already close to its limit. A water heater on an already-stressed circuit causes overheating, which causes failures and occasionally fires. We've seen this many times.
There's a second Bali-specific factor people underestimate: humidity. A connection that looks fine on the day you make it can corrode within months in a poorly ventilated bathroom, and a corroded terminal under a heavy continuous load is exactly how arcing and overheating start. Professionals seal and torque connections specifically with this in mind; a DIY install rarely does. Add to that the fact that spare parts, the right cable gauge and a proper RCD-protected circuit aren't always easy to source locally, and the "saving" from a full DIY job can evaporate the first time something goes wrong.
The water connections are more forgiving than the electrics, but there are still two things people get wrong. The first is the pressure-relief valve: it must be fitted and its drain piped to somewhere safe, because that valve is what stops a faulty thermostat turning your tank into a hazard. Skipping it or capping it off is genuinely dangerous. The second is the cold-inlet / hot-outlet orientation — connect them the wrong way round and the heater either won't fill properly or won't deliver hot water where you expect. If you're hanging the unit yourself, take a photo of the old connections before you remove anything so you can match them.
If your property runs on hard well water, if the existing circuit is old or shared, if you're fitting a gas instant heater (ventilation and gas connections are not a DIY job), or if you're installing solar on a roof — call a professional from the start. In these cases the risk and the complexity outweigh any saving, and a botched install often costs more to put right than doing it properly would have in the first place.
If you want to save money: buy the unit yourself and hang it yourself. Then call us for the electrical connection. Labour for the electrical part only is IDR 300,000–400,000 — much less than the full installation cost, and you still get it done safely.
Questions about a water heater in your Bali property? WhatsApp us — free advice, no pressure.