We install many spray parks each year and the repeated question is, what about clean water and safety?
In the past few years there has been increase in the number of Recreational Water Illness (RWI) issues(example Cryptosporidiosis) associated with splash pads, water parks, spray parks.
Just look at your water source:
By using the current municipal water system you are able to use the cleaned and filtered water for the local waste water treatment plant. So instead of installing an expensive local system, use what you already have.
You can local treat your system, but you MUST check it regularly to make sure it is doing its job. For most cities it is tough to find the people service guys to do this. You probably bought a spray park, splash pad, or water park for having less people on staff then a pool. There are several treatment ways out there so please explore all the options when looking at a system like this.
Concrete is recommended by most manufacturers as it allows proper drainage. If you use a rubber surface then bacteria can build up and the surfacing will no doubt break down. The chlorine and constant water, UV and foot traffic just wears it down. So you have added long term cost of ownership.
Check out the CDC website on healthy swimming in water parks, splash pads and spray parks
Also, check local codes for rules in your area.
Also, the CPSC has come out with some new guidelines for water parks.
In the end, you need to focus on clean water, proper drainage and spray park maintenance!
I found this fun picture at - http://www.tenafly.k12.nj.us/~asandt/exploring_bacteria.htm