To try to cut a long story short, we had rats in the last dump we rented & finally figured out they were coming thru the ensuite bathroom floor waste which was conveniently hidden under & behind the bath tub with no cap on it.
When we moved into the new dump we are renting there were no caps on both the bathroom floor wastes or in the outside pembantu's squat toilet (not that we have or need a pembantu ). I'd noticed there was rat crap near the squat toilet so put ½ a brick over the waste but after it got moved & there was more rat crap evident I put a heavier river stone over the waste & problem solved.
On the other two internal bathroom wastes I put metal sink strainers because I couldn't find where to get the proper fitting caps which are not the standard screw & lock type,
Well, something kept moving the metal cap in the downstairs toilet but we found no rat crap & the rat poison we put out didn't get touched so we thought it may have just been the volume of water from the shower pushing the cap a little to the side or the kids inadvertently kicking it as they had a shower (yeah, blame the kids).
Silly me, remember I related how we had 2 baby cobras in the house & wasn't sure if they were one & the same,... & the lizard in the kitchen which in her fright my wife called a crocodile? As if that wasn't enough for her, last night at about 10pm she woke with a startle & said “a rat just ran over me”, she then jumped up & in a trembling voice(unable to scream) said “Ular”. I sat up thinking WTF, another baby cobra & said “turn the light on”, well this thing was at least a metre & a half long but not a cobra thank God, it was some kind of python I'd seen before which at first glance looks very much like the poisonous Australian brown snake.
With the lights on during Nyeppi it took me about 15 minutes to chase the thing out of the house while my wife stood on the coffee table in the lounge room, she then said “what about the rat”. I said “look for it willya” & when she found what was actually a very small mouse she was straight back to the coffee table leaving me to chase it out as well.
We then saw that the cap on the waste in the bathroom had been pushed completely off the hole so today I put a heavy river stone over it too & hopefully that will be the end of our little in house wildlife adventures.
Forgot to get a happy snap but here's a snap of one of the baby cobras