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The ins and outs of plumbing

If you want to connect water pipes and taps all by yourself, you’ll discover that this is often easier than you thought. Of course it would be useful to know in advance which pipes are going to be used and when, and you’ll need to take the right pipe diameters into account. This page offers some basic information to help you get started.

Water supply and drains

Tap water and water for flushing the toilet are basic human needs, so they have to meet strict standards of quality. That’s the reason why pipes, sealants and other materials have to be used safely, in such a way that no health risks could occur. Therefore, it’s important to only use materials which are allowed to be used for your drinking water supply.  Make sure to check that the pipe has the KIWI hallmark on it.

Materials used for the water supply pipes and drainpipes

Water pipes these days are made from copper or PVC. If you use PVC pipes, make sure to check if they’re heat-resistant! All modern drainpipes are made from unbreakable, heat-resistant, dimensionally stable PVC. Any bends in the drinking water pipes should generally be made by adding a soldered joint or compression fitting. Bends in drainpipes are done using L-shaped, T-shaped and Y-shaped connectors.

Various diameters

Different sizes are used for each type of plumbing material. This can be confusing! Pipes and fittings with a screw thread are measured in inches, while PVC pipes are measured in inner diameter and millimetres. Copper pipes are measured in outer diameter and wall thickness. The different sizes correspond as follows:

The pipe thicknesses generally used for drinking water pipes are 12×1, 15×1, 22×1 and 28×1.5 (outer diameter x wall thickness in mm). The same measurements are also used for PVC pipes.

Which sizes to use and where

The diameter of the water pipes goes down step by step from the water meter to the tap. Vertical pipes that supply water to various floors are always at least 20 mm in diameter. This corresponds to 22×1. 15 mm pipes are used on the upper floors. This corresponds to 15×1. Make sure to ask someone at the building centre about the best approach for your specific situation. Different sizes are used for drain pipes. For example, a 40 mm drain pipe is connected to small sinks, wash basins and bidets. A 50 mm drain pipe is used for kitchen sinks, washing machines and dishwashers, bathtubs and showers. 110 mm pipes are used for toilet drains and fallpipes. If more than three pipes are connected to the same junction, if the pipe has multiple bends, or if the vertical distance is more than 50 cm, you should use one size bigger than advised above.

Soldering, brazing and Unipipe

Copper pipes are soldered together with tin, a technique known as soldering. If the pipe connections are bigger than 25 mm in diameter, then they are brazed; It’s a similar technique, but uses a copper-zinc alloy. Such large pipes are generally not used indoors, so there’s no need to take a closer look at brazing. If you need to use larger diameters, please ask Novo for advice. These days, copper pipes are only used when really necessary. Most of the time, we use Unipipe, which offers a better, more durable alternative to copper. Plus, these joints use a crimp connector that can be closed with crimping pliers: fast, easy, 100% water-proof, and long-lasting. A great innovation in plumbing since the 1990s!

DIY waterworks

Feel free to handle all the plumbing and waterworks installation yourself inside your home, except for the connections to the water mains and sewers. For those major connections, please contact Novo to discuss your options.


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