One of the criticisms of Reverse Osmosis filtration is that they add to your water bills
It's true that RO does waste water in that 50% to 70% of the incoming water is rejected by the filter while it's purifying the water.
But let's look into this in detail:
This wastage only involves the relatively small amount of drinking / cooking water you use ie not all the water in your home.
On average, only about 3% of domestic water in the UK is used as drinking/cooking water.
So it's not quite as bad as it first seems.
But it is a factor.
Let's Checkout the Financial Cost:
In the UK at the time of writing, one cubic metre (ie 1,000 litres) of water costs around £3.00
Let's say that's 0.3 pence per litre
You should drink at least 2L of water a day. And let's say you use another 2L in cooking. That's 4L a day.
But let's call it an average of 6L a day per person for drinking and cooking water.
Now let's assume 70% of this is wasted (that's the upper end. It's probably less than this).
So the 6L x 70% equals 4.1L every day of wasted water.
That adds up 1.2p per day
Per month it's 123L wasted. So that costs 40 pence per month per person...
Bear in mind that these calculations have exaggerated the likely usage to 5L / per day per person. It could easily be half this - especially in a family setting
The Green / Carbon Cost:
Also bear in mind that this "wasted water" goes into the drain where it is recycled by the local water company.
Overall Reverse Osmosis water purification is a huge carbon saving on buying bottled water - while giving you much better quality.
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