How do i contact welsh water? Please contact Welsh Water on: 0800 260 5051 If you are not an Open Water customer, but you have questions, please contact Welsh Water on: 0800 052 0145 The types of charges available to our Open Water customers.Who is glas cymru? Since 2001, we have been owned, financed and managed by Glas Cymru. Unique in the water and sewerage sector, Glas Cymru is a company limited by guarantee and as such has no shareholders. The Glas Cymru business model aims to reduce Welsh Water’s asset financing cost, the water industry's single biggest cost.Who is welsh water owned by? Since 2001, we have been owned, financed and managed by Glas Cymru. Unique in the water and sewerage sector, Glas Cymru is a company limited by guarantee and as such has no shareholders. Welsh water is a not-for-profit company.