Best way to add extra water carrying capacity (on the bike)

https://www.halfords.com/cycling/bike-accessories/bike-bottle-cages/elite-water-bottle-cage-strips-680223.html

I’ve had these on two bikes and they were both completely fit and forget. Tape underneath them if you like you paint unscuffed.

I used to use this on my hardtail, worked perfectly well.

Is filtering water an option?

I bought a water-to-go filter bottle after a recommendation on here. I've used it loads on longer rides. It's a bit of a game changer.

I wouldn't filter any old water, but I've used it a lot from small streams up on the moors/tops away from farms and never had a problem at all.

https://watertogo.eu/product/75cl-active-bottle-black/?gad_source=1&gclid=CjwKCAjw8rW2BhAgEiwAoRO5rEiAejsGJ-vtEUi3K9TmJNG2iMmyedS6jQFVIFImdsu1kJG8EN60NhoCkWUQAvD_BwE

I've used a rubber mount (from Decathlon) that worked well attached to the forks of my Fatbike.

However, the Water-to-go bottle is now my regular carry on such rides.

Those Decathlon bolt on mounts are pretty nice, but maybe not so sturdy if you're riding rough terrain.

How about a stem bag? Easy to access the bottle and to remove from the bike when you don't need it.

I've used:

Frame bag with bladder

Handle bar bag with bottle

Topeak zip tie on bottle cage mounts. https://www.topeak.com/global/en/product/1093-VERSAMOUNT

For loads of water- frame bag and bladder. Mine is 2l

For one bottle the topeak zip tie on bottle mount works exact as a bottle cage.

Could you fill all of the frame's tubes with water and then drink from there?

thats what i thought.  bung up any holes and add a straw to the top tube?

I use one of these to give me a 2nd bottle on my FS mtb and a third bottle on my cross/gravel bike.

https://www.alltricks.com/F-41481-accessoires-de-transport/P-1465727-lyne_holy_rail_dual_cage_kit_black

Topek also do a bottle cage mount that fits 22mm bars, gives you the option to add another bottle cage or two on the bars.

Have also used some of those zip tie on types before and all good.

James

I know you said on the bike, but how about two 250ml soft water bottles on the back pockets. Drink them first and they weigh nothing. Thats what I do when needing to take extra water.