Byelaw 30 and Byelaw 60 kits

Byelaw 30 kits and Byelaw 60 kits consist of a set of components designed to protect the water in a cistern from contamination. They are intended for mains-fed cold water storage cisterns and feed and expansion cisterns, and are either supplied with a new cistern, or can be purchased separately if one is looking to upgrade an existing installation. The variation in name is due to the separate legal systems in the UK, namely England and Wales, and Scotland. The main difference between the two kits is the diameter of the overflow: a larger diameter is stipulated by the Scottish Byelaw 60.

The kits generally consist of a screened overflow pipe, an overflow dip tube, a rubber grommet for the expansion/vent pipe, and a breather fitting. In compliment with the cistern lid, they play an instrumental part in keeping the water in the cistern free from dirt and debris. Depending on the manufacturer, some kits may include a Part 2 ball valve and/or a small ball valve backing plate.


Cisterns fed from the mains form an important part of any household plumbing system. Without any protection, they will ingest unwanted debris from the loft, risking the blocking and contamination of your plumbing systems.

Byelaw 30 and Byelaw 60 kits typically include the following items:

  • A rubber grommet, to create a sealed admission point for the expansion pipe/vent pipe.
  • A screened breather, fitted into the lid in order to prevent the formation of condensation inside the cistern and keep it at atmospheric pressure.
  • A screened overflow pipe, to prevent anything outside, such as insects, from entering the cistern.
  • A dip tube, allowing the overflow pipe to dip into the water so that cold drafts cannot enter the cistern.

The difference stipulated by the different codes is that the overflow dip tube must be 38mm (1.5 inch) in order to satisfy Byelaw 60 in Scotland, whereas 22mm (3/4 inch) is suitable for Byelaw 30 in England and Wales.

Water regulations also require that cisterns have a close-fitting lid which will not react with the water, and will retain its structural integrity should it get wet. The lid plays a vital role in keeping any animals from getting into the cistern, such as insects, rodents or even birds.

Some byelaw kits may include a small plastic backing plate, which is secured to the outer cistern wall via a nut on the stem of the ball valve. This reduces stress to the cistern wall from the upward force of the float. Some byelaw kits may include a ball valve – usually a Part 2 model.


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