Washing litterbox

Hello,
1000 apologies if this topic is out of place but I'm not sure where to post it.
I've always washed the litterbox with soap (handsoap) and water, rinsed well in hot water and so far cats hadn't rejected it or had an adverse reaction.
But it could happen, right? I mean a cat could be allergic to a certain soap,etc..I just wondered what do you recommend..it'll be a first one for my present kitty. Thank-you!
A great 2004 to everybody <<))