OK I know this subject has been done to death but, rather than going through all previous threads, can I have a quick summary of likely causes. The facts...
Ruby is the culprit. No obvious health probs and no blood in urine. 8 month old kitten in a house with her twin sister and 4 other cats. All get on except her mom but mom's hardly ever in apart from meals times. A fair bit of chasing goes on esp with Billy but if anything I'd say Ruby was pretty self assured. Neighbour's cat Butu was telling Ruby off the other day in our back garden but she stood her ground.
There are 3 cat trays, 2 large and one enormous. The kittens use the trays, the cats hardly ever. Cats have 24/7 indoor/outdoor access; kittens are allowed out when we are about and locked in overnight. I'm going to wash and disinfect the trays again tomorrow but I keep them pretty clean and Ruby's sister Millie uses them with no problem.
Looking back, the peeing has been going on for a while but is becoming more frequent. Peeing used to be on carpet in hallway, now is in bathroom (in bath and now on floor) and 2 poos now too. Have now wedged bathroom door shut. Ruby also pees on the lawn which I've never known a cat do before.
Neither kitten appears to drink much water. They are fed on a mixture of wet and dry food 4 times a day with 4 water bowls dotted about the house.
So, apart from vet visit to rule out probs, any ideas please?