Water tanks - is this a problem

[jdillon]

I was in the loft of my new house and noticed this water tank had its cover off.
So a number of questions:

1. I thought the big tank was the water one, whats the smaller one?
2. It doesn't look very clean, does it matter and if so, what can I do?

 

[terryplumb]

Small one feeds central heating/boiler.
Large one feeds hot water cylinder and possibly some cold water outlets, but not kitchen sink.
Both should be covered ,and the small one would benefit from cleaning out.

 

[jdillon]

Thank you!