Up here Thames Water charge the same rate for the water used as they do for the waste/sewage water - basically what goes in costs the same as what goes out, so by definition they don't charge for surface water disposal. Edit: Got that wrong - there is a fixed charge for surface water treatment, in addition to the actual water supplied and removed costs.
Not quite. Sewage works have storm tanks to take the surplus which then gets pumped back and treated. Once these are full it all overflows though.
Dont try and defend the ******* the overflow facilities are best described as crap. One of the harbours in which many people undertake water-sports down on the south coast in 2020 saw many many occasions where the water company pumped overflow water including raw sewage into it. Often for days at a time, the longest was only 4.5 days. I went for a swim in the summer and was very ill for a week after. The regulation of water companies seems pretty poor and when they get caught they dont seem to give a Marmite.
Defend storm water overflows - not me, though I've got a pretty good understanding how they got to be like that. It's not that long ago that discharges of crude sewage were permitted in tidal waters. Then membership of the EU made coastal towns install treatment. It really was much worse at one time but it's still got a way to go.
The river Usk running through the middle of Newport city centre - you could play poo-sticks any day of the year. Didnt see Winnie and Christopher Robin once.