We see that water, and to a lesser extent, electricity supplies have been hit badly by flooding.
It is understandable that a water treatment works was taken out of service when it was inundated if they are configured as I remember when visiting Beckton Treatment Works many decades ago (and boy, that was a fun, if smelly day out!). Floodwaters tend to end up as very dilute sewage, so allowing that mix to slosh into the water treatment ponds can render them unusable until cleaned up. That decision to close the plant is acceptable.
What is NOT acceptable is how one treatment works out of action means so many houses without ANY piped water. I suspect this fragile state of affairs is replicated across the country.
A major part of this is due to the monopolistic structure of the water supply industry. We have privatisation, but we are subject to geographic monopolies, which are against our best interests.
I have posted before that monopolies are a bad thing, but sometimes necessary or pragmatic in certain limited areas. The area where it is pragmatic is in the DELIVERY of water. It is NOT pragmatic in the treatment and SUPPLY of fresh water. Had our water system only retained a geographic monopoly in delivery infrastructure and not treatment and supply, people would still have their water as the delivery infrastructure would be so arranged to enable a plurality of sources to feed any given area - a "National Water Grid", as it were. Such an arrangement would be in place to enable price and quality competition to occur. It would also be possible to equalise supplies in times of drought. When a treatment works is knocked out for whatever reason, it would then not result in what looks to be WEEKS without water, though possibly a time of lower pressure.
Electricity substations are far harder as they are, in effect, part of the distribution network, stepping down voltage as it gets closer to habitation. However, I suspect they are far easier to defend due to their smaller footprint.