Around 2,500 private homes and businesses in Den Bosch have paid no water rates since 2011 because the local water authority forgot to send out the bills.

They have now received a letter pointing out the omission and telling them they will have to pay what is owed. It is not yet clear how much money is involved, says Nos television.

Local water authority BSOB says it is sorry for the situation and that it realises back payments could put some people and companies into financial difficulties. It is therefore arranging for the debts to be paid off in instalments.

It is now clear why no water rates have been charged since 2011. The mistake came to light in December 2013 during an internal audit.

Also in December, Amsterdam council discovered it had paid out too much in housing subsidies and needed to reclaim €188m. It is still trying to get back €4m.