Question: How can scrap metal clean poisoned water? Surely it would add lots of lots of toxins?

Harriet Aitken answered on 15 Jun 2014:

Ah, a very sensible question! It seems really silly that you could use something dirty to clean something but it has a lot to with how some chemicals get into water in the first place.

One of the ways dangerous chemicals enter natural water, for example underground wells, is by the breakdown of the rocks surrounding the water undergound. Some metals are found in rocks and minerals that may also contain dangerous chemicals. If these rocks break down and dissolve in water, like a sugar cube in tea, chemicals that were once bonded with the metal containing rock or mineral enter the water supply.

A lot of science is about working backwards to the solution, so when scientists discovered that’s how those chemicals entered the water they thought – well why can’t we put them back? Certain chemicals are attracted to the rust forming by the corrosion of the scrap metals which removes the chemicals from water.

There is one big problem with this – you then have dirty rusty water, but rust is actually a very big particle which you can remove using a filter. You can even use sand to filter rust out of water, which is great because sand is very very cheap, like rust!