Kitchen Renovation Plumbing: What We Do, When, and What You Have to Decide First

Kitchen plumbing is a smaller scope than a bathroom, and it goes wrong in different ways. There is no waterproofing to argue about and nothing hidden in a wall cavity. What there is instead is a lot of appliances, a benchtop that other trades have to install, and a set of decisions that have to be made before anyone can start.

This is the order it actually happens in, and what we need from you at each point.

How many visits, and when?

Two visits for most kitchens, occasionally three.

Visit one: cap-off and pre-line. Before the old kitchen comes out, we isolate and disconnect what is there: the sink water and waste, the dishwasher, the disposal, and the gas if there is a cooktop. Then, while the walls and floor are open, we run the new supply and waste pipework to wherever the new layout puts them. This is the visit where changing your mind is cheap.

Then the kitchen gets built. Cabinets go in, the benchtop is measured and made, and the benchtop is installed. That is not us.

Visit two: fit-off. With the benchtop in and set, we install and connect everything: sink, mixer, dishwasher, disposal, filter, fridge waterline, and reconnect or cap the gas.

A third visit happens when an appliance arrives late, a part has to be ordered, or a variation turns up. We would rather tell you that is a possibility than pretend every kitchen is two clean visits.

Who installs the sink? (It is not us)

This is the question we get asked most, and the answer surprises people.

The benchtop trade installs the sink into the benchtop, not the plumber. On a stone benchtop the sink is bonded in and needs 12 to 24 hours to set before anybody touches it. We turn up after that and connect it.

So the sequence is: benchtop measured after cabinets are in, benchtop fabricated, benchtop installed with the sink in it, setting time, then us. If we arrive and the sinktop has not set, we cannot do the job, which is the most common reason a fit-off gets moved.

What we do install is everything that connects to it: the mixer, the wastes and traps, the dishwasher and disposal connections, and the filter.

What has to be decided before we start

Pre-line is the cheap moment. After the benchtop is in, changes cost real money.

Sink: how many bowls, and undermount or top mount. This affects the benchtop cut-out, not just us, so it has to be settled with the cabinetmaker.
Mixer, and whether it is a pull-out. Pull-out sprays need room to move under the bench.
Dishwasher: which side of the sink. Distance to the waste matters.
Waste disposal, or not. It needs a power point under the sink, which the electrician needs to know about early, and it changes the waste arrangement.
Filter, and what kind. An under-bench filter with its own dedicated tap means a second hole in the benchtop. Nobody can drill that later.
Fridge waterline: yes or no. More on this below, because it is the one people do not understand.
Gas or induction. If gas is going, that is a cap-off. If it is staying, it is a disconnect and reconnect with a certificate. More on switching to induction.

A recent Golflands kitchen is a typical scope: sink water and waste set up, new mixer, new dishwasher, gas cooktop disconnect and reconnect with the Certificate of Compliance, and a Puremix under-bench filter supplied and installed. All of that had to be known before we ran the pre-line.

The fridge waterline

We ask every client about this and a fair number ask us what it means, so plainly: a waterline is a small water supply run to the fridge, and you only need it if your fridge has a water or ice dispenser in the door.

If yours does, it needs a water connection at the fridge position, and the time to run it is at pre-line while the wall is open. If it does not, you need nothing.

Worth checking your fridge specifications rather than guessing, particularly if the fridge is being replaced as part of the renovation. Retrofitting a waterline into a finished kitchen means going back into a wall or running pipe where you can see it.

Appliances: what we do and what we do not

We connect appliances. We do not carry them or make them fit.

We can move a dishwasher into position and connect it. What we cannot do is force a machine into an opening it does not fit, and that happens more often than you would think when an appliance was chosen without checking the cabinet opening. If the dishwasher will not go under the bench, that is a cabinetry question, not a plumbing one, and we will tell you on the day rather than forcing it.

Disposal units are the other one. At a property in Tiroroa Avenue the air switch button had stuck in and was not returning, so we replaced the switch at no charge. The unit still behaved abnormally afterwards, which pointed at an electrical or motor fault inside the machine, and our recommendation was that the disposal itself would need replacing. We will confirm whether it is the plumbing or the appliance, but we do not repair the inside of appliances.

At Central Park Drive a dishwasher was leaking. We found the connection had been fitted incorrectly and re-fitted it properly, then ran a test cycle, and water still came out of the back of the unit itself. That is an appliance warranty claim, and we said so.

After the fit-off: the dry towel

We leak test everything before we leave. We also put a note on every kitchen invoice saying there is a less than five percent chance of a minor leak showing up later, because a waste disposal or a dishwasher moves slightly in use and a connection that tested dry on the day can weep once it is being knocked about.

If that happens, put a dry towel underneath, take a photo and ring us. It is covered, and it is exactly what we ask people to do rather than something to feel awkward about.

The same trick finds any leak under a sink: dry the cabinet, tuck paper towel around each connection, use the kitchen normally, and see which one is wet. More on that here.

Working with your kitchen company

A good deal of our kitchen work comes through kitchen companies rather than directly, and the scheduling runs off their programme: site measure, benchtop template, benchtop install, then plumbing fit-off.

What that means for you is that our date moves when the benchtop moves. We would rather confirm the day before than turn up to an unset benchtop, so if your benchtop date shifts, tell whoever is coordinating and it will reach us.

We are also plumbers and gasfitters, so where a kitchen involves both, the gas cooktop and everything under the sink happen in one visit with one point of contact rather than two trades booked around the cabinetmaker.

Planning a kitchen? Send us the plan and we will tell you what we need decided and when.

Common questions

Do I need to be home?

For pre-line it helps, because layout questions come up. For fit-off it is less important as long as we have access, but it is worth being reachable, since that is the visit where appliance and tapware questions arise. If you cannot be there, leave the appliance manuals out.

When should the appliances be on site?

Before fit-off, in the room, unboxed if possible. We cannot install a dishwasher that has not arrived, and an appliance still in its carton in the garage on the day is how a third visit happens. The fridge can come later unless it needs a waterline connected.

Can you reuse my existing tap or filter?

Often yes, and it is worth asking rather than assuming you need everything new. We reused an existing filter tap on a Beachlands kitchen recently. What we will tell you is if something is at the end of its life, because refitting a worn mixer into a new kitchen is a false economy you will pay for twice.

What if I want to move the sink to a different wall?

That is a bigger job than it looks, because the waste has to run with fall to reach the existing drainage, and how far you can go depends on the floor and where the drain is. It is very doable in many houses and impossible in some. Ask at the planning stage rather than after the cabinets are ordered, because the answer can change the layout.

Is the gas certificate automatic?

For gasfitting work that requires it, you should get one, and on a cooktop reconnect we need a photo of the finished installation showing the wall surfaces behind it and the rangehood before it can be issued. Keep the certificate; it is what an inspection or an insurer will ask for later.