The firms clarified their positions after Thames Water said could soon end restrictions following rain in April and May.
The Environment Agency said earlier that reservoir stocks had improved significantly, with further restrictions unlikely. However, the agency said it was still making plans with water companies for a potentially third dry winter in a row.
The other two water companies with restrictions in place – Southern and Anglian – are monitoring the situation. Southern said it could be possible to lift them “much sooner than expected” depending on rainfall and demand over this month.