Firstly thank you for taking time to read this for me. Last week we were lucky enough to have our second daughter born. During getting some bits out of the roof I looked at the cold water tank as it was running. I’m a complete novice at plumbing but can fix a few things. To be honest I didn’t realise the cold water tank did anything except fill up the immersion tank for hot water when the boiler is on. However it was running because someone was running the cold tap in the kitchen. I looked inside and could see some bits floating around then a algae looking film on the bottom. It has a lid and is plastic. I saw a small spider floating as well. I then realised this is our drinking water! I immediately worried and decided to only use bottle water to drink. Especially with a week old baby to wash etc. So my question is how do I clean it out and do I have to use it? It seems as all the cold water and hot water taps are fed from this yucky tank. The two toilets flush and fill up without the tank water so they must be direct and that is what I would like all the cold water to come from? The boiler is a Glow worm flexicom 12hx and presume it heats the water in the immersion tank which gives us our hot water and also the central heating. The immersion tank must be fed from the yucky cold water tank so that’s not good either? Does this boiler need a cold water tank? Or an immersion? Need some help and advice as I don’t have the money for a call out charge of a plumber yet until I know what I’m dealing with. Thanks for any help