Ah but you see, the market will determine the real punishment, as informed consumers will now punish thames water by withdrawing their business (and forgoing drinking water, showers and laundry etc). This makes it all more efficient you see.
Absolutely ridiculous, stream premier league football get 11 years in jail. Dump sewage and ruin the rivers get £3.3m fine while making 100x that yeah seems legit.
Perhaps a new requirement for the board at Thames water: Every time they dump sewage in their river, a valve is activated that dumps sewage in their living room.