How is the water company calculating my monthly direct debit?

Posted by romeo__golf@reddit | AskUK | View on Reddit | 25 comments

I pay my water bill by 6-monthly bill, largely because I can pay by credit card and get airmiles in the process, but I'm completely thrown by how they calculate the expected direct debit if I were to switch.

In October my bill for 6 months' usage was £190.74, effectively just under £32/month, but they suggested a payment of £52/month.

This week I received another 6-month bill for £214.68 (£36/month) but they've suggested a payment of £57/month on direct debit!

I appreciate they might want to make the payment a little higher to allow for changes in usage, but these suggested monthly payments are 60% higher than my actual usage.

Does anyone have any insight into why they do this beyond "they just want to hold your money"?