· 5 min read · Taylor Plumbing
A new dishwasher looks like a simple job, slide it in, connect a hose, plug it in. But a rushed installation is one of the more common sources of slow leaks under kitchen cabinetry, often not noticed until the base of the cabinet has swollen or the flooring has lifted.
Here's what we check on every dishwasher install to make sure it's sound for years, not just working on the day.
Water supply connection
Most dishwashers connect to the cold water line, though some models can run off hot for faster cycles, check the manual before assuming either way. The connection should always run through its own isolating valve, usually a small valve under the sink cabinet dedicated to the dishwasher, so it can be shut off on its own without affecting the rest of the kitchen.
Waste connection
The dishwasher's waste hose needs to connect either to a dedicated waste spigot on the kitchen sink's waste trap or to the sink's air gap fitting, and it needs to loop up higher than the dishwasher's base before running down to the waste. This high loop, or a proper air gap, stops dirty sink water siphoning back into the dishwasher.
Skipping the high loop is one of the most common corner-cutting mistakes we see in DIY installs, and it can mean waste water backing up into the machine during a sink drain.
Checking for leaks properly
- Run a full cycle after installation, not just a quick water fill
- Check under the machine and behind it, not just what's visible at the front
- Check the fittings again after 24 hours, some slow leaks only show up after the first few cycles
- Make sure the cabinet base isn't already showing signs of old water damage before you seal the new machine in
Levelling and fit
A dishwasher that isn't level won't drain properly and can put uneven strain on the door seal over time. It also needs to sit clear of the joinery on all sides so the water and waste hoses aren't kinked or under tension, which shortens their life.
Power and electrical safety
Dishwashers need a dedicated power point, usually installed by an electrician with the right circuit rating, positioned so the cord isn't pinched or resting in a puddle-prone area. If you're renovating, it pays to have the plumber and electrician coordinate on power and water positions before the cabinetry goes in.
Replacing an existing dishwasher
When swapping an old dishwasher for a new one, it's worth checking the existing isolating valve and waste connection rather than assuming they're still sound. Valves can seize or corrode over ten-plus years, and a waste hose that's perished is easy to miss until it's under pressure again.
Frequently asked questions
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Dishwasher installation and replacement across Christchurch. New builds, renovations and swap-outs.
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