The weather apps inform me we're in for some Decent Weather, I'm fully aware the apps are often false prophets but it seemed a good time to make this post anyway. Hopefully it'll be useful at some point even if the apps are lying.
As the proud owner of a 5 year old daughter I've become pretty au fait with the splash pads in the area. I can very confidently state Gheluvelt park is the absolute best. The parking is atrocious and it gets absolutely rammed but it's still the best! It is that good.
The postcode for the car park is WR1 3EY, it's useless and far too small for the park. You're better off looking for a space on the surrounding side streets which is what everyone else seemed to do too. The disabled parking is at The Pump House Environment Centre on Waterworks road.
We went on a really hot day and it was lots of fun. My daughter was two and prior to going I was slightly concerned she might be a little bit too young for it, we went anyway because the park itself is lovely and if the splash pad had been a fail for us there were other things to do. The splash pad seemed to appeal to a very wide age range, there were little toddlers right up to 12/13 year olds. There's lots of jets, spouts and geysers and a little pool. It seemed to have a lot more equipment and features than the other ones we've visited. Check out this blog post about outdoor photography so you can capture your time in the park.
The park itself is so nice and very much worth a visit even if the splashpad is off. The park has a decent playground, toilets, a good cafe at The Pump House Environment Centre, tennis courts, a lake, bandstand, lots of green space for picnics (Make sure to bake some of these lovely custard cookies for your picnic) and running around, outdoor gym equipment and outdoor table tennis. You can read more about the park on the Wikipedia page here.