Installing an Instant Hot Water Tap: What to Expect

An instant hot water tap is a two-part system: the tap on your worktop and a heated tank under the sink. Installation is straightforward for any RGI-registered plumber but there are a few things you should sort before they arrive.

Before the fitter arrives

• Under-sink space: minimum 400mm height clearance for the tank.
• Power: a standard fused 13A spur within 1m of the tank.
• Waste: existing waste pipe can be reused; no changes needed.

The fit itself

• Isolate mains cold at the stopcock.
• Cut a 35mm hole in the worktop (already drilled on most modern sink units).
• Mount tap, connect braided flexi lines to the tank.
• Wire the tank to the fused spur, prime with cold water, power on.
• Let the tank reach temperature (~20 minutes) then flush 2 litres through before use.

Total time on site: 60–90 minutes.

After install

The tank holds boiling water at 98°C indefinitely. Descale every 12 months (kit included) and replace the filter every 6 months for best taste.