Originally Posted by Askartus

There are mainly two "parts" in the Therme Erding: One for adults with Saunas and Poolbars serving fresh Erdinger Weißbier (nice after a visit in a sauna) named "Vital-Oase" and "Saunaparadies". And another with slides and fun stuff for everyone named "Thermenparadies" and "Galaxy" (which is the part with the slides).
That being said: It can be quite full during weekends and holidays. You should also watch out for holidays in Austria or Italy as they do day trips to Erding as well (we were there two years ago on an austrian bank holiday and waited 20 minutes just to get in!)

Imo Therme Erding is great family fun, if it is not crowded. If the adults want to visit the sauna area, please be aware that only 16+ yo are allowed in there.

BTW: Erding itself is quite nice to stroll around as well and maybe it is an idea to visit the brewery of Erdinger, while being there already. S-Bahn access from Munich is possible.