Safe to drink but (often) not good enough for your wildlife pond

UPDATED: See the comment from my Pond Conservation colleague Chris Monk which neatly shows how, especially in the north, it’s worth checking the quality of your tapwater.

This post is partly in response to Sue’s comment yesterday that she was regretting filling her new pond with Yorkshire Water’s best.

Well, sadly, it looks as though she was right to worry.

Taking Sue’s postcode I checked the quality of her drinking water.

This will work for most of the big Water Companies in England and I think in Wales. I haven’t checked whether the same information is on-line in Scotland and Northern Ireland where there are different arrangements for drinking water supply.

First I went to the company’s website – in this case Yorkshire Water.

Dragging yourself away from the irresistable offers for iPhones and emergency plumbing you choose the Water Quality tab.

Under that you’ll see a sub-heading called ‘Check your water quality’ and a link to ‘View Water Quality Report‘.

Click the link and up pops this page where you enter your postcode.

Enter your post-code and you get this page – a summary of what’s going on in your postal district.

It really is an excellent site!

At the bottom left of the screen you’ll see a link to the pdf copy of the Annual water quality report for your postal area.

This is based on detailed analysis of hundreds of laboratory samples of water from the tap in the relevant area.

It’s gobbledegook unless you know quite a lot about water chemistry – but there it is, in full detail.

There’s a map showing the area the report covers – in this case part of York and the surroundings.

And then a page of detailed results – covering everything from Arsenic to……I was hoping for something that begins with Z, but for some reason Zinc is not regarded as important in drinking water (it is a regularly present water pollutant – mostly from decaying car tyres – but presumably the levels are not dangerous for people).

It’s also worth noting that the water companies don’t usually measure phosphorus – the other very widespread pollutant in freshwater that is not actually harmful for people but has had a huge impact  on freshwaters.

Here’s one of the detailed pages.

Click to see this more clearly

On the second line down you can see the value for nitrate – in this case the average value (called the mean here) in the last but one column on the right is a fraction over 21 milligrammes of nitrate in each litre of water.

This is of course a tiny amount but its very large by natural standards – roughly ten times what you would expect naturally. In my pond, the value a couple of weeks ago was just over 1 milligramme of nitrate per litre of water – so 20 times lower.

So, sadly, Sue was right to regret putting tapwater in her pond.

In many parts of the United Kingdom our tapwater, though treated to a very high standard and safe to drink, is not really good enough for a wildlife pond.

This is mainly due to the very high levels of nutrients, particularly nitrogen, present in our drinking water supplies.

Add that to you pond and hey presto – instant pollution.

But it is worth checking because not everywhere will be as bad as this.


4 Responses to “Safe to drink but (often) not good enough for your wildlife pond”

  1. Chris Monk Says:

    To show how the quality can vary even within a county, here at the Sheffield Wildlife Trust office where the South Yorkshire Ponds Project is based the tap water has an average nitrate content of only 2.6 mg/l and a conductivity averaging 155. Thats because the water comes from reservoirs up on the edge of the Peak District where there is no intensive farming spreading fertiliser and muck over the ground, only low intensity sheep grazing on moorland.

  2. Joe Berry Says:

    Where do you stand on partial water changes, Jeremy? Presumably if a pond has been filled with tap water, removing half the water and replacing it with rain water would dilute the pollutants by half?

    I was thinking a series of these partial changes would be better for a mature pond (with lots of plant growth and microfauna) than a total water change.

  3. Sue Says:

    Thanks for all your efforts Jeremy – although I rather think I might have been happier being left in the dark! I’ll be interested to see your response to Joe’s query re partial water change. It would be an impossible task to drain and refill the pond now (we’re no longer youngsters – the original work was done for us) but I reckon we could haul out some water and refill from the water butt – maybe on a regular basis.

    Thanks for your excellent blog by the way.

  4. SHELDON Says:

    we adore this blog post. i have alerted my friend donny about this because he likes this sort of information too!

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