The list below contains current members of MOSL. View a list of all Water company appointments.
| MOSL Member Legal Name | Membership Type | Licence Type | Portfolio Manager |
|---|---|---|---|
| Advanced Demand Side Management Ltd | Unassociated retailer | WSSL | Pam Nash |
| Affinity for Business (Retail) Ltd | Associated retailer | WSSL | Pam Nash |
| Affinity Water Ltd | Wholesaler | IoA | Pam Nash |
| Albion Eco Ltd | Associated retailer | IoA | Pam Nash |
| Albion Water Ltd | Wholesaler | IoA | Pam Nash |
| Anglian Water Services Ltd | Wholesaler | IoA | Pam Nash |
| Anglian Water Business (National) Ltd | Associated retailer | WSSL | Pam Nash |
| Arla Foods Limited | Unassociated retailer | WSSL | Julie Carly |
| Berendsen UK Limited | Unassociated retailer | WSSL | Julie Carly |
| Blackpool Borough Council | Unassociated retailer | WSSL | Julie Carly |
| Bristol Water PLC | Wholesaler | IoA | Julie Carly |
| British Telecommunications PLC | Unassociated retailer | WSSL | Julie Carly |
| Cambrian Utilities Limited | Associated retailer | WSSL | Pam Nash |
| Castle Water Ltd | Unassociated retailer | WSSL | Liz D'Arcy |
| Clear Business Water Ltd | Unassociated retailer | WSSL | Liz D’Arcy |
| Coca-Cola European Partners Great Britain Limited | Unassociated retailer | WSSL | Julie Carly |
| ConservAqua Ltd | Unassociated retailer | WSSL | Pam Nash |
| County Water Ltd | Wholesaler | IoA | Pam Nash |
| Dwr Cymru Cyfyngedig | Wholesaler | IoA | Pam Nash |
| Everflow Ltd | Unassociated retailer | WSSL | Liz D'Arcy |
| First Business Water Ltd | Unassociated retailer | WSSL | Pam Nash |
| Greene King Brewing and Retailing Ltd | Unassociated retailer | WSSL | Julie Carly |
| Hafren Dyfrdwy | Associated retailer | IoA | Liz D'Arcy |
| Heineken UK Ltd | Unassociated retailer | WSSL | Julie Carly |
| Icosa Water Services Ltd | Wholesaler | IoA | Pam Nash |
| Independent Water Networks Ltd | Wholesaler | IoA | Pam Nash |
| J Sainsbury PLC | Unassociated retailer | WSSL | Julie Carly |
| John Lewis PLC | Unassociated retailer | WSSL | Julie Carly |
| Leep Utilities (formerly SSE) | Wholesaler | IoA | Pam Nash |
| Leep Water Networks Ltd | Wholesaler | IoA | Liz D'Arcy |
| Marston's PLC | Unassociated retailer | WSSL | Julie Carly |
| Northumbrian Water Ltd | Wholesaler | IoA | Liz D'Arcy |
| Olympos Water Limited | Unassociated retailer | WSSL | Liz D'Arcy |
| Pennon Water Services Ltd | Associated retailer | WSSL | Julie Carly |
| Portsmouth Water Ltd | Wholesaler | IoA | Julie Carly |
| Regent Water Ltd | Unassociated retailer | WSSL | Pam Nash |
| Scottish Water Business Stream Ltd | Unassociated retailer | WSSL | Liz D'Arcy |
| Sefton Council | Unassociated retailer | WSSL | Julie Carly |
| Severn Trent Water Ltd | Wholesaler | IoA | Liz D'Arcy |
| Smarta Water Limited | Unassociated Retailer | WSSL | Julie Carly |
| South East Water Ltd | Wholesaler | IoA | Pam Nash |
| South Staffordshire Water PLC | Wholesaler | IoA | Pam Nash |
| South West Water Limited | Wholesaler | IoA | Julie Carly |
| Southern Water Services Ltd | Wholesaler | IoA | Julie Carly |
| Sutton & East Surrey Water Services Ltd | Associated retailer | WSSL | Pam Nash |
| Sutton & East Surrey Water PLC | Wholesaler | IoA | Pam Nash |
| Stonegate Ltd | Associated retailer | WSSL | Pam Nash |
| The Water Retail Company Ltd | Unassociated retailer | WSSL | Pam Nash |
| Thames Water Utilities Ltd | Wholesaler | IoA | Pam Nash |
| Thames Water Commercial Services Ltd | Associated retailer | WSSL | Pam Nash |
| Three Sixty Water Ltd | Associated retailer | WSSL | Liz D'Arcy |
| Tor Water Ltd | Unassociated retailer | WSSL | Julie Carly |
| United Utilities Water Ltd | Wholesaler | IoA | Liz D'Arcy |
| Utility Bidder | Unassociated retailer | WSSL | Pam Nash |
| Veolia Water Retail (UK) Ltd | Associated retailer | WSSL | Julie Carly |
| Veolia Water Projects Ltd | Wholesaler | IoA | Julie Carly |
| Water Plus Ltd | Associated retailer | WSSL | Liz D'Arcy |
| Water Plus Select Ltd | Associated retailer | WSSL | Liz D'Arcy |
| Waterscan Ltd | Unassociated retailer | WSSL | Julie Carly |
| Water2business Ltd | Associated retailer | WSSL | Julie Carly |
| Wave Ltd | Associated retailer | WSSL | Pam Nash |
| Wessex Water Services Ltd | Wholesaler | IoA | Julie Carly |
| Whitbread Group Plc | Unassociated retailer | WSSL | Julie Carly |
| Yorkshire Water Services Ltd | Wholesaler | IoA | Liz D'Arcy |
| Yü Water Limited | Unassociated retailer | WSSL | Liz D'Arcy |