Sunday, 31 May 2020

Water saving again

Siphoning the bath water into the water butt.
Rainfall has been very low for the last few months across the country but especially so in the East of England. Our water butt ran very low a couple of weeks ago and we have resumed emptying bath water into it. We now have a shorter hose and attachments which makes this much easier!

Here in Cambridge we get our water from an aquifer which protects us from short term droughts, but last year the level dropped to record lows and there were serious problems with low flow in important chalk stream habitats. The level did recover this last winter, but I fear a repeat this summer, if we are not careful with water. Please do what you can. Here is some more background on the issue and some water saving tips.

Recently rainfall has been very low.
This chart shows monthly rainfall data from the Cambridge Digital Laboratory. The data set goes back to 1996 so more than 20 years. In the chart, the solid line shows the last 12 months and the dashed lines show ranges over previous years. Q50 is the median and Q10 is the level where only 10% of months were worse. March, April and May were all below average, March was close to the 10% worst and May was actually a record low.
Rainfall in Cambridge over the last 12 months compared to normal ranges, using data from the from the Cambridge Digital Laboratory 

The aquifer level can drop quickly, with severe impacts on natural ecosystems.
Three months is not a long drought but our water supply is less resilient than it used to be. Over five months from May to September 2018 the aquifer level dropped from a near record high to well below normal, and then with the dry winter it never recovered leading to critically low levels the following spring. The problem is getting worse partly due to climate heating: although overall our rainfall is not obviously decreasing our summers are hotter and the growing season is longer which means we use more and there is less water available to recharge the aquifer. The effect on the natural environment would be even more acute except that the water companies pump water directly into certain chalk streams to keep them flowing. Unfortunately this is only a partial solution as the water runs into the stream bed and dries up downstream. You might like this simulation tool I have on my website, to show the impact. I have written more on this on the Transition Cambridge website here.

Try exploring your water use with a water calculator.
Cambridge residents are about the national average when it comes to water use. I am sure we can do a lot better. You can try this water calculator (also on my website) to explore your own water use and how you can make savings. There are lots of tips on how to save water at home on the Waterwise website and also on the Cambridge Water website.

What we do at our house.
At our house we have efficient toilets but even so we avoid flushing the loo if it is likely to be used again soon. A lot of our water use is for showers. Also we do have two baths a week but we empty the bath water into the water butt now so that is not such a waste. Plants do not mind soap or detergent. (It can kill aphids which is not such a bad thing. I am not sure about using greasy washing up water on the plants but water from washing or even cooking vegetables is fine. We now use a bowl for that so we can reuse the water in the garden. When washing our hands we always turn the tap off while lathering and on again at the end - a full 20 seconds of tap running is a lot of water.

The new, improved bath siphoning process.
We now have a dedicated hose for siphoning the bath water into the butt. This is just long enough (fortunately the water butt is directly below the bathroom window so 6m is enough) and it has attachments at both ends with a tap to shut off the flow. This is a huge improvement on before where I would be invariably sprayed with water between detaching the hose from the tap and sticking a bung in. The procedure now goes like this:
  • Open the taps at both ends.
  • Lower the hose into the bath a bit at a time so it all fills with water.
  • Close the taps at both ends.
  • Take one end and lower it out of the window into the water butt.
  • Open taps at both ends, keeping the bath end below the water surface all the time.
  • Trap the bath end with a weight to keep it down while the bath drains.

1 comment:

  1. Hi - great article, thank you! Love the water calculator, but it would help if it would cope with decimal values. For instance, my children (share) a bath once a week (showering on other days). This requires a 0.25 value for number of baths a week if 4 people are entered in the people field. It would be good if communities could ‘compete’ to drive down water consumption. We have a leak in our village at the moment - very wet road. :-(


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