I found this little gem after googling " outdoor pools west midlands"
We went on a family trip once we had the heads up it was going to be 24 degrees that particular day. When we arrived half of Worcester was also queing outside and we waited in the sweltering heat for an hour and a half to get in as 2 hours after opening the gates it was full to capacity!
It was well worth the wait as it is a fabulous place for the family. The pool was clean, modern and facilities excellent. The children loved the pool, complete with the little beach area for younger children. It is well laid out too as as a parent you can relax on the side still in good viewing of the children as it's all on one level. We took a picnic as there were picnic tables and also deckchairs to lounge around on. It really was a great day out and only £12 as we bought a family ticket for 4 people. Definitely recommended. The only tip is to arrive early to avoid the queue. Simply lovely though.