Kitchen Plumbing
Safe, Quiet and Long-Lasting Water Connections.
In modern kitchens, hot and cold water distribution, the sink, mixer tap, dishwasher, water treatment system and waste pipe must all be professionally planned together.
Request a Quote for Your Project →Kitchen plumbing is the infrastructure that safely supplies every point of water use in the kitchen.
If the sink, mixer tap, dishwasher, filter system and waste connections are not planned correctly, leaks, odours, low pressure and difficult maintenance can result.
Kitchen plumbing comprises hot water, cold water, appliance supply lines, water treatment connections and waste water discharge. As there are many connection points inside the units, the system must be installed in a tidy and serviceable manner.
Correct planning makes tasks such as replacing a mixer tap, servicing filters, connecting a dishwasher and cleaning drains much easier. It also reduces the risk of hidden leaks and damp inside the units.
Which water connections in the kitchen must be planned correctly?
The most common connection points in kitchen plumbing are described below, together with the materials used, dimensions and technical details to watch out for.
Sink and Mixer Tap Connections
The sink is the most heavily used water point in the kitchen. As the hot water, cold water, mixer tap connection, filter outlet and waste pipe are often grouped in the same unit, the connections must be tidy, accessible and leak-tight.
Separate outlets are usually provided for hot and cold water for the mixer tap. Fitting mini ball valves or isolating valves at the connection points under the worktop allows the mixer tap to be replaced or a filter fitted later without shutting off the water to the whole apartment.
PEX, PE-RT, PPR, multilayer composite or copper pipe can be used for the water lines. In modern kitchens, a manifold system or under-worktop distribution connections may be preferred.
Technical installation details
| Pipes used | PPR, PEX, PE-RT, multilayer composite, copper |
|---|---|
| Typical supply pipe diameter | 16x2 mm, 20x2 mm, PPR 20 mm / 25 mm; varies by project |
| Waste pipe diameter | Usually a Ø50 mm waste pipe for the sink |
| Points to note | Valve access, hot/cold orientation, trap connection, service space inside the unit and leak testing |
Dishwasher Water and Waste Connection
Dishwasher plumbing consists of a water supply and a waste water outlet. For safe operation, the inlet line must be controllable by its own valve, and the waste hose must be connected to the trap at the correct height.
A faulty waste connection can cause odours in the machine, dirty water to flow back, water to remain inside the appliance or leaks under the unit. A dishwasher connection should therefore never be treated as simply attaching a hose.
Technical installation details
| Water connection | Usually a 3/4” dishwasher hose connection |
|---|---|
| Supply line | Cold water line; a hot water connection may be considered if the manufacturer permits |
| Waste connection | To the trap or a separate waste outlet; usually Ø40 / Ø50 mm |
| Risks | Backflow, odours, kinked hoses, inaccessible valves, leaks inside the unit |
Water Treatment and Filter Systems
Under-sink filters, carbon filters, reverse osmosis systems or drinking water treatment units can be used in kitchens. For these systems, the water supply, treated water outlet, waste water discharge and a separate drinking water tap connection must be prepared correctly.
A reverse osmosis system does not just filter water; it also produces a certain amount of waste water. The waste hose must therefore be connected securely to the trap.
Technical installation details
| System types | Carbon filters, sediment filters, reverse osmosis, mineralising filters, UV-assisted systems |
|---|---|
| Connections | Cold water supply, treated water outlet, waste water discharge, drinking water tap |
| Maintenance | Filter cartridges must be replaced regularly; the membrane and tank pressure must be checked |
| Points to note | Service access, waste connection, low pressure, leak sensor and use of valves |
What should you consider when installing kitchen plumbing?
1. Connections must be accessible.
Valves for the mixer tap, filter and dishwasher must be easy to reach inside the unit, so that work can be carried out without shutting off the water to the whole apartment.
2. The waste pipe must be connected at the correct fall.
An incorrect fall in the sink and dishwasher waste can cause odours, blockages and backflow.
3. The hot water line must be insulated.
Insulating hot water pipes reduces energy losses and helps hot water reach the tap more quickly.
4. A pressure test must be carried out before handover.
The water supply line must be pressure tested before the units, worktop and finishes are completed.
Let’s plan safe, well-organised plumbing for your kitchen.
We will install the sink, mixer tap, dishwasher, filter system and waste pipe so that they are long-lasting, accessible and leak-tight.