I know its been hot and fuid intake increases but I think this is something more.
She is demanding a drink constantly, and guzzles each one down, at a guess at least 7 -8 pinta day, now am I right in thinking if she was drinking all this extra purely because of the heat, then she would sweat most of it out, because she seems to be just peeing it out, and it seems to go through her very very quickly, for eg, I put her down for a nap with a fresh nappy on, when she woke 90 mins later, she and the bed were soaked through.