When considering which tap to buy, two important considerations will dictate the environmental impacts of your decision; the material and manufacture of the tap, and its water delivery when in operation. This article considers a consumer’s options in relation to the second issue.
Defra produce a Water Technology List that includes all products that meet their water efficient eligibility criteria. These products are eligible for 100% Enhanced First-Year Capital Allowances when purchased by businesses.
There are two main ways of setting performance targets for taps and showers; through the use of target flow rates and by limiting the flow rate from exceeding a maximum level.
- Flow rate – typically described in terms of litres per minute for a given level of pressure. This rate will vary depending on the pressure, with a lower pressure delivering a lower flow rate. As an example, Grohe’s K4 kitchen tap delivers around 9 litres per minute at 0.5 bar, 12 litres per minute at 3 bar and about 13 litres per minute at 5 bar.
- Limiting flow rate – limiting the maximum flow rate of the tap or shower through the use of a flow restrictor or a flow regulator. If the later, the flow rate should not exceed the specified flow level for pressures up to and including 5 bar. E.g. if the maximum flow rate of a tap is 6 litres/ minute then the flow restrictor should cap the flow rate at 6 litres/minute for pressures up to 5 bar; in order that the system doesn’t exceed 6 litres irrespective of its pressure.
Two other ways of increasing a tap’s water efficiency are:
- Water break function (sometimes known as ‘eco-click’) – introduces resistance to the lever movement, limiting the flow to about 50%. To get a higher flow, further force must be applied to overcome the brake. Whilst most manufacturers set the break to a default 50% flow, it could be set much lower for suitable functions.
- Aerating – mixing air into the water flow as it leaves the tap so each water droplet consists of a skin of water around a bubble of air, saving the amount of water required for the same flow.
Both of these kinds of products can be found on the Waterwise products list as well.
