Drinking Water 6 March 2013 Andy Case CEnv C.WEM BSc (Hons) MCIWEM
About me • Run Case Environmental, Teignmouth based environmental consultancy established in 2009 www.caseenvironmental.co.uk • Worked in the water and environmental industry for over 10 years, including South West Water and the National Trust • Work across Devon & Cornwall and further afield looking at mainly private water supplies and related issues.
Water – The Facts • 70% of the surface of the Earth is water • 98 % sea water • 1.5 % ice • 0.4 % found in aquifers, rivers & lakes • 0.1 % atmosphere, plants & animals
Clean Water • 800 million don’t have access to clean water • 3.5 million die of drinking water related illness each year • 700,000 of these are children – approximately 2000 per day • In developing countries half of all hospital beds are filled with people suffering from poor quality water & sanitation.
Sources • Rivers • Reservoirs • Groundwater (springs, wells and boreholes) • What about sea water?
Sources - Groundwater Spring Borehole Well
Source to tap? Reservoir Town ££££ Meter
Typical Mains Water Treatment for Surface Sources Flash mixer Chlorine contact tank Sand filter Clarifier Carbon filter Phosphoric acid added Coagulant added pH corrected Chlorine added pH corrected To final water tank and distribution Inlet
Source Water Quality • Heavy rain - spate conditions • Run-off from fields – animal waste, fertilisers, pesticides • Operation of combined sewer overflows • Diffuse pollution – pesticide degradates, nitrate • Industrial pollution • Fuel/chemical spills • Algal blooms • Saline intrusion
Source Water Quantity • Needed most when less is available • Areas with the least rain have the biggest demand for water • Most rain falls in winter • Minimum abstraction levels • Recharge rates for aquifers
Water Supply in the South West • Big population variation, in summer some areas can double • Seasonal rain fall expectations • Topography • 33% of the countries coastline • 2.5% of the population • Over 30 water treatment works • 600 sewage treatment plants
Drinking Water & Climate Change • Many issues already surrounding production and distribution of drinking water • Very power & chemical intensive to operate & supply – if oil/gas supplies stopped we’d have no water • Importance of sustainable water management; - SUDs, allowing aquifers to recharge, limit run-off - Land management (chemicals, crops, livestock etc) - Water security.
Water Use Water use has increased from 90 litres per person to 180 litres per person in 50 years – why? • People want to be cleaner • Appliances such as dish washers & washing machines • Gardening • Increased car ownership
Water Saving Measures • Showering – reduce time, fit aerator to showerhead • Use washing machines/dishwashers only when full • Invest in efficient goods • Bowl in sink (washing, food preparation) • Modern toilet/water saving device • Check for leaks – not just taps but toilet overflows • Garden – grow plants that require little water, protect from wind & sun • Outside – avoid using the hosepipe
Alternative Water Sources – Rain? Roof collection • Average roof size of 80m2 • Average rain fall in South West UK 800mm per m2 • Annual amount 64 m3 Other points of collection? • Patios/drives • Outbuildings
Rain Water Benefits • Naturally clean • Reduce run-off/flooding, contribute to sustainable urban drainage • Potential saving £150/year • Reduce demand on mains Problems • Acidic – pH correction or plastic plumbing needed • Maintenance • Can collect debris/detritus from roof – first flush needed • Position of tank to be useful • Storage & potential bacterial concerns • Technically need to inform SWW so they can charge you sewerage
Alternative Water – Grey Water • Either partially treated water or previously used water • Limited uses due to quality • Require modification of existing plumbing • Treatment required, cost implication, servicing • Potentially harmful to plants and environment depending on previous use • Microbiological issues with use – legionella etc.
Way forward? • Encourage rainwater harvesting in new builds? • Sustainable Urban Drainage? • Variable rate billing? • Wash less?