RS water meter 1/2" BSP part no. 399-5018
Digital meter (resettable) part no. 433-3758


Hope this helps.

Peter

We have a similar set up I installed on our water tank and watermaker. You simply need to purchase a domestic water meter with a digital pulse output. These are common on ebay in the UK. The pulse output needs to be one pulse per litre. The meter will come with a two core cable. To this cable you connect a digital pulse counter. These are also available on Ebay. The cost of the meter on Ebay is about £40 and the pulse counters are about £7.
We have this set up on the main tank so once we fill the tank we reset the counter to zero. On the first time use you need to let the tank go to empty. This reading is your tank capacity. From now on you know exactly where you are with tank content to the nearest litre.
With the same set up on our watermaker we know how much we have made and how much we have used. Works brilliantly and all for less than £100

Hi Simon
We were lucky enough to have had a water meter fitted as standard on our Jeanneau 45 and it has proved to be an excellent piece of kit. The parts are available from RS. Peter

We always used to rely on float gauges to monitor water use and engine hours to monitor fuel use when cruising. In our experience water float gauges were pretty useless so then we got thinking about using in-line meters. We tracked one down in the USA which measured use in litres, didn 't require a power supply, could be reset when the tanks are filled and can be read remotely. It has been brilliant. I now know exactly how much water we have used and what we have left. I can thoroughly recommend fitting on and we are thinking of adding on to our fuel line too. I am sure there are many on the market but the one we use is shown below.


[attachment=104]image_2013-08-29.jpg[/attachment]