Archive for August, 2009

How do you measure water filter efficiency?

Water filterI'd like to buy a highly efficient water filter to make healthy, potable, odourless drinking water in my home. The tricky thing is, how do you measure efficiency?

There is a debate going on at MetaEfficient about what constitutes efficiency. The reverse osmosis water filtration process is put forward as a solution even though it consumes electricity and outputs more waste water than it outputs drinkable water. Does that sound efficient to you? Me neither. The meta-efficiency is measured as follows:

"When assessing a product, we consider not only its energy efficiency but also its embodied energy, toxicity, affordability, and usability."

That's sensible, but you can't roll all these things into one score because they are measured by different means. Furthermore, people have different perceptions of what is important. $100 might be a lot of money to me but it could be cheap to you. Environmental impact might be important to you but it might be critical to me.

The solution would be to rate products on separate factors and provide multiple scores, e.g.

  • Life Cycle Assessment (LCA): taking all environmental impact into consideration, measured in a unit such as joules. Incredibly hard to do accurately.
  • Usability: gauging how well it does the job and how easy it is to use. Scored out of 100.
  • Retail price: in £/$/€
  • Running cost: in £/$/€

Only when you separate the important aspects of a product and measure each one in an standard unit can you compare products effectively.

It takes a true geek to do such in depth research and comparison for water filtration systems. It will happen eventually – the internet's global reach makes in-depth comparison a viable business proposition. But in the meantime, can anyone point me in the direction of a highly efficient household water filter, regardless of cost?

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