Took mine out of the bag last night, was horrified at what I saw – and go knows how long I’ve been drinking out of it in that state. Never put anything in it other than water or High5, but somethign has grown in it.

Is Milton the best option? Or the bin?

Water + scrub out using the camelbak cleaning kit first to get most/all of the gunk out then fill it with water + milton and leave it overnight to sterilise. Don’t try what I did once and try and fill it boiling water, unless you like boiling water over your leg caused by the bladder melting that is…

it all help to strengthen your immune system dun it?

Miltons, and a scrub round is all I do. Normally it just the tube that gets really manky, and you can replace that easily enough, if it doesn’t clean up.
I bought the CB cleaning kit years ago and use it every couple of months [edit] then soaking it overnight in miltons (other cleaning kit or DIY solutions are available).

I put a Milton tab in mine if it’s been left for ages. Usually just keep it in the freezer between rides so it doesn’t go manky.

Don’t forget the bite valve. So many bugs etc in your mouth that this can get a bit ropey as well.

Scrub til it looks respectable. Then Milton.

I think, but wise to check, that platypus reservoirs can be boiled – but not camelbaks.

Isn’t High5 as likely to fur up a reservoir as anything?

Bleach / toilet bleach is your friend – I used a liberal amount to clean an old camelbak a few years back, left it in there with some water overnight and all the black gunk had turned white and flaky by the follwoing day. Washed it out a few times and it was good as new. First ride or two it tasted ever so faintly of chlorine but this soon passed.

If you sterilise it, don’t forget to empty the sterilising fluid from the tube as well as the bladder.

Otherwise expect a nasty surprise when you take a huge mouthful at the top of the first climb BLEEEEEUUUUUUURGH!!!! 😳

If its really horrid i’d suggest a slosh out with warm water just to remove the loose stuff, then soak over night in water/household bleach mix (just a little bit of bleach – its pretty strong stuff) the next morning bleach should have cleaned it up nicely.
Rinse out and if you really want you could clean out with either milton or sterident – but there should be no need.

In future rinse out with clean water after each use and store in the Freezer – a rinse out with Milton from time to time can only help aswell…

Be carefull with supermarket own-brand snyde ‘Milton’ tabs – they work great but might bleach your clothes, whereas proper Milton wont… my Mrs discovered this when washing out baby bottles in ASDA own brand ‘Milton’ – and splashed it down her skirt.