Are we short of water? | | DJS

Are we short of water?

Are we short of water? In the UK, that famously wet place?

I began with [91], which turned out to be accurate in fact but puff in delivery and, having read it all twice, and bookmarked it as useful, binned it. Instead I'll take the title and run with that. Here's the world view, which says to me that the UK sits on the ocean and so gets rain from weather coming usually from the West. It's the way the world turns, you know.

In the South-East of England, the average annual rainfall lingers around 500-600mm – drier than South Sudan, or Perth, Western Australia  [91] 

The UK’s average annual rainfall is a sopping 1200 mm, compared to the 300s in Afghanistan, or just double-figures in Egypt. [91] I've found that data, blue bars above left.

It is true that SouthernEngland (Kent to Dorset,  the Met Office [92]) has lower rainfall than the rest of the UK.

 Much of Southern England is relatively distant from the route of many Atlantic depressions and towards the north-east of the region there is increasing shelter from rain-bearing SW winds. This shelter reaches its greatest potential around the Thames Estuary. The wettest areas are therefore the South Downs and the higher parts of Dorset, with an average of over 950 mm per year. In contrast, the Thames Valley, London and the North Kent coast normally receive less than 650 mm of rain per year, and less than 550mm around the Thames Estuary. These values can be compared with annual totals around 500 mm in the driest parts of eastern England and over 4000 mm in the western Scottish Highlands. [...] If a period with below average rainfall includes winter months as well as the high-demand summer months, then conditions can become severe as the winter is the normal recharge time not only for reservoirs but the chalk aquifers upon which much of the region relies for water supplies. [92]

I know from previous experience that rainfall is surprisingly variable and found that is true for the planet, as shown on the line graph to the right. 

 The latest Government Water Abstraction plan [93] shows that 28% of groundwater aquifers in England, and up to 18% of rivers and reservoirs, are unsustainably abstracted. Only 17% of England's rivers are classified as being in ‘good ecological health’. [91] 

This is a presentation issue. [93] actually says Latest data show that 82% of surface water bodies and 72% of groundwater bodies have enough water to protect the environment, providing good support to fish and other aquatic life. Sustainable surface waters have enough water to support ecology. In rivers this means enough flow. Sustainable groundwater bodies meet the four tests explained above. However, we know that abstraction in 8% of surface water bodies and 28% of groundwater bodies is unsustainable.    An additional 10% of surface water bodies are identified as potentially unsustainably abstracted. In these cases the Environment Agency is collecting further information to confirm whether river flows are sufficient to support ecology. This information will be used to reclassify the majority of these water bodies as either sustainably abstracted (green) or unsustainably abstracted (red) by 2021.

My read of [93] says 'we're on the case'. It doesn't say much about whether the situation is improving or worsening, but it does say they expect improvement in 2021 (stated in July of that year). We have a general issue (man has) with use of aquifers and replenishment of these. It is as if we need a charging meter.

Are we short of water and are we likely to be? 

The very first line of [95] says the average person uses about 150 litres of water a day. Is that a bad thing, if we have lots of water? Yes, apparently it is. Do we have too little water? Only in the sense that we (think we) are accustomed to having an unlimited supply. With climate change an issue, we can be much more efficient in our use of water, not least the energy use attached to water. I was amused at the London-centric view that pushed its way to the front of so much of this report; the South and South-East are high density, affluent – and drier, as explained above. That lack of rainfall explains in part why the capital is there. Mind, I felt that the tone of the whole document [95] was just a little self-satisfied, as if the world is seen through rose-tinted spectacles.

The magic word here is sustainable. It rains and we have water; we cannot afford to extract water in excess over rainfall except in the very short term and, across a small number of years we have to show that we have, indeed, sustained our water levels. Water is too heavy to treat it like gas or electricity. I can see sense in talking about a National Grid for water (I mooted it in the drought of 1976), but the economics don't work at all well.

Figure 1 of [95] says 55% of all water use is by households and the adjacent text repeats the 150 litres per person per day. No doubt we could quite easily use less. I worked out from our domestic bill that we use 100 litres a day (that's 2sf not 1sf) and that we have done that consistently. We don't use a bath and we do water the garden; we have low flush toilets. We (two) disagree about the volume of a shower by a factor of at least two and about the washing of food before preparation. We don't collect rainwater for the garden, though we could. I fill the pond often. So while our use is markedly lower than the average, I think we could very easily drop that by 20% with hardly noticing the change. Yet, for the average to be so high, others are using a lot more than twice what we do.

Figure 3 from [95] shows that, in comparison to the EU (rest of, 2006) we're pretty much in the middle, assuming that national comparisons work.

Around 7% of the water we use in our homes is for drinking and cooking.  Almost a third of the water we use is, after being treated to what is among the best drinking water quality standards in the world, at significant financial and environmental cost, simply used to flush our toilets. [95, p21 comment 5]  Which says to me that fixing the flush mechanism in the house, as I have done for each of the three we've owned since 2014, makes a significant change to water consumption. Our consumption is a little under 100 litres per person per day.

None of which answers the question of whether we're actually short of water. Yes, we're wasteful. Yes, we use very clean water for purposes that do not justify the work that went into cleaning the water.

1993-2005 I lived in Cornwall in a house that was built with a dual water system. Drinking water came out of a well; other water come out of the sky, off the roof and into a very large tank above the bathroom, with capacity for several tonnes. Thus washing water and toilet water were not confused with potable water. Of course, some previous owner had been prevailed upon to modernise and have piped water. The rules for abstraction are difficult and the water table had moved by the time we lived there, but the possibility to switch remained. It made me think that we could probably all do something about rainfall in terms of using it before letting it soak into the ground.

Being consistent in letting these things write themselves as I fumble through the jungle of available information. I tried to explore how well we store water. Which means reservoirs and how much they carry in reserve over predicted demand. Sir James Bevan, CEO of the Environment Agency, said, in 2019, “Around 25 years from now, where those [demand and supply] lines cross is known by some as the ‘jaws of death’ – the point at which we will not have enough water to supply our needs, unless we take action to change things,” Bevan told the Guardian, before a speech on Tuesday at the Waterwise conference in London. Within what he said we expect the typical 140 litres per person per day to drop to 100 (mostly through fixing the loo and using a shower instead of a bath, see Maths), but we also need to do a lot about the losses from the water network to half of its current value.  Of course there are several actions; reduce our demand, waste a lot less, make the system better, store more water — and other actions.

We have a lot of reservoirs, but maybe we don't have enough. We build them rarely and we have made this a difficult thing to do, such os the level of local opposition to any change. You would think the calculation for need fairly straightforward; we use <this> much, predicted to change like <this> and the rainfall pattern is varied but changing like <this> so we need <this> available to avoid having shortages or worse. So we need <this> sort of amount in storage to cover the dry periods by storing from the wet ones. As Mrs May said, simples. Or so you would think. Factor into this that the movement of water is rapidly expensive (yeah, it's mostly free if going downhill) – I still like the idea of exporting excess water in Scotland down south to England, but it would probably be cheaper to move people and call that migration 'levelling-up'.

There's the idea of virtual water, which is a bit like measuring your carbon footprint, in that, if you count the water used in the manufacture of what you consume (food, particularly, such as rice at 3400 litres per kg, cheese at 5000, beef at 15500 [is that double counting)? then that 140 or 150 litres per day becomes, in Britain, more like 4645 litres. Per day.    [97,98]. This means that, one way or another, we in effect import water; Only 38% of the UK's total water use comes from its own resources; the rest depends on the water systems of other countries, some of which are already facing serious shortages. [97]. I think this could well reduce to having resources properly priced and to put enough emphasis on sustainability; there is little point in exporting fresh food if at the same time you are extracting more water than the country has. This may well be seen as a result of greed, or as a failure to co-operate, or as an economic failure, not pricing things correctly.

DJS 20211203

[91]  Oh dear, a biased rant. I read this, fact checked it and found little wrong, except that everything is coloured with the bad-news-sells vibe. I was going to make a long page out of this article, but it really isn't worth it.



[94] Why is the most recent figure for only  2017?

[95]  refers to water in England. The other nations have an easy surplus; it rains more and they have a far lower density of population.

[96]   Item from Sky binned as empty beyond the headline. Sir James Bevan CEO of the Environment Agency in 2019 said, “Around 25 years from now, where those [demand and supply] lines cross is known by some as the ‘jaws of death’ – the point at which we will not have enough water to supply our needs, unless we take action to change things,” Bevan told the Guardian, before a speech on Tuesday at the Waterwise conference in London.



[99]  reporting about this report   We may yet have wars over water. 

Losses per day are around 3 billion litres.  BBC source  Elsewhere, the BBC reported in 2018 In the UK as a whole, about 23% of the water put into the public supply is lost because of leaks. In July 2020 this looked very good,  reporting that mean usage had fallen since the last report from 143 to 142 litres per day per person, that overall loss was down by 7% to 2954 Million litres, 8 million litres a day.  We would be wrong to say that this is then not our problem to work on, that this is someone else's (the water companies') problem; the system is enormous and there will always be leaks. They can be fixed better, faster, etc but they will still exist and occur.  An irritating site to view (for me). We need to do our part and reduce demand.

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