An agreement over water is to be made which will see powers shared between the UK and Welsh governments.
The UK Government currently has powers which mean it could intervene if it believes devolved functions risk having a 'serious adverse impact' on water resources, water supply or water quality in England.
The new deal will mean UK ministers will no longer be able to intervene in decisions made in Wales.
The Consumer Council for Water (CCWater) says written complaints from customers against water companies in Wales have fallen again but says there is still more to be done.
Written complaints against Dee Valley Water fell by more than 28 per cent, while Wales’ biggest water company Dwr Cymru Welsh Water also saw a drop of over 14 per cent.
Dee Valley Water’s complaints fell at twice the rate of the previous year while Dwr Cymru Welsh Water reduced written complaints for a third successive year, meaning they are now only half what they were in 2004/05.
Severn Trent Water also saw written complaints fall for the second year running, down by nearly 14 per cent.
A plan by the UK government to increase competition in the water supply sector is "unlikely to work in Wales".
A committee for the National Assembly says it's unconvinced the new Water Bill would result in increased benefits for customers.