Ladies i need your advice/ideas....

My little girl is almost three months and has just about outgrown her baby bath. She obviously can't sit up yet on her own, and i'm in a bit of a pickle. The problem is (isn't that we don't have a bath already)rather our bath is a large triangular spa shaped one and so takes a fair bit of water to get even a little bit full.

I know that my mum is getting one of those bath seats (but its recommended for 6months+) and will be of use only when bubs can sit up on her own. How should i go about bathing her? Bath time is at night, and hubby doesn't get home until late so i can't even have a shower and get DH to pass her to me.

In the current times of water restrictions, and water consumption per household, i can't justify running a bath for her every night (when she is only laying there for a couple of minutes and not being able to play)...Any ideas or tips would be really helpfull!!!!

Hopefully this makes a bit of sense to someone!...

Thanks All