FTSE 100 water firm Severn Trent and engineering company Costain have announced a joint venture to provide business water and wastewater management services to high volume commercial users.The new entity, Severn Trent Costain, will offer large multi-site water users a single expert supplier for all of their water and waste water requirements, from source to disposal.Severn Trent will control 60% of the joint venture.Tony Wray, Chief Executive of Severn Trent said: "Costain is a long term partner of Severn Trent Services and together we have already established a track record for successful delivery in the UK."Andrew Wyllie, Chief Executive of Costain, added: "Severn Trent Costain will help customers to manage their water and waste water usage in the most efficient, compliant and cost-effective way. Increasingly, customers are looking for a single expert provider who can help plan and manage their industrial water and waste water use across the full cycle."BS