Water Quality. making it crystal clear

Transcription

1 Water Quality making it crystal clear

2 Water Quality Facts South East Water supplies top quality drinking water to more than 2.1 million people each day. The quality of your drinking water is monitored at every stage of the treatment process from the raw water through to the water which comes out of your taps. We take samples every day to analyse at our laboratory in Frimley, Surrey to ensure the water is safe to drink and that we are complying with Water Supply (Water Quality) Regulations 2000 (as amended 2007). The DWI (Drinking Water Inspectorate) also monitors the quality of the drinking water we supply to our customers and audits the company. Taste and Odour Water tastes differently depending on whether it has been taken from a river, reservoir or underground aquifer and sometimes we may need to alter the source of your supply. However, some customers occasionally report that their tap water has either an unpleasant taste or odour. Taste and odour issues are sometimes difficult to identify and require a process of elimination. Is the taste / odour coming from the kitchen tap? What time and for how long have you noticed the problem? Have you had any work completed recently on the internal or external plumbing of the property? Are your neighbours experiencing similar problems? Is it only noticeable after boiling or with hot drinks? Have internal water storage tanks been checked? In any property, fittings in the household plumbing system may impart some taste issues as water acts as a solvent for many materials it can dissolve trace amounts of metals, plastics and rubber. Furthermore, minute amounts of chlorine may also react with some parts of these fittings and this can cause an unpleasant taste. However, these taste issues might persist if the fittings and fixtures are of poor quality and do not conform to British or equivalent European standards or a specification approved by the regulator. The Water Regulations Advisory Scheme (WRAS) can provide advice on appropriate tap fittings.

3 water quality facts Common taste and odour issues include: Chlorine/TCP/bitter/disinfectant/medicinal By law we have to make sure that the water you receive is pure and safe to drink and we add small, carefully controlled amounts of chlorine to the water to maintain its bacteriological quality. The chlorine addition is continuously monitored and controlled within strict limits. However, on occasions some customers can notice a chlorine taste and/or smell but it is essential that drinking water should be safe to drink and contain no harmful bacteria. Chlorine is not harmful in the quantities we add to the water supply. It is a balancing act between adding sufficient chlorine to prevent bacterial growth in the mains and keeping it at a level where a taste or smell is rarely noticed. The chlorine concentration does reduce with time and the amount experienced at any point in the distribution system will vary depending on several factors, in particular the customer s proximity to a treatment works and the demand and therefore the flow of water. At time of relatively high usage, such as the early evening, the concentration will be higher than at time of lower demand.

4 There are no specific standards referring to chlorine in water. It is our policy to have a measurable quantity of chlorine present at customers taps. This helps maintain good water quality and also keep the distribution system in good condition. If you do notice a taste or smell, then one simple way of reducing the chlorine concentration before preparing drinks is to store a jug or container of tap water in the fridge ready for use. Please do not keep any water which has been stored more than 24 hours as it should be treated like any perishable food. In addition, chlorine evaporates out of water when it is boiled, so this is another way to eliminate any chlorine smell and taste. Alternatively, these tastes and smells can also be caused when small amounts of chlorine reacts with rubber or plastic found in kettle gaskets/seals, tap/internal stop cock washers, hose pipes connecting dishwasher and washing machines. This rubber contains phenol which, when it reacts with chlorine form trichlolophenols TCP, which while harmless to health, can cause taste problems at extremely low levels and produce a taste stronger than chlorine itself.

5 If you do have strong TCP-tastes or smells from your water, please try these helpful tips: Use water that has been stored in a jug in the fridge to drink and to make your hot drinks. If you have not used your tap after periods of non-use, try running it for a couple minutes. Check with your neighbour to see if they have same problem. Make a note of which tap or fitting you were using when the problem started. If necessary, replace the washer or fittings. Rinse your kettle out before you use it. If you suspect your kettle may be causing the taste try boiling the water in a saucepan and use this water to make your hot drinks. If you have a washing machine plumbed into the mains in the kitchen check it has a suitable non-return valve fitted so that water sitting in the hose over long periods is not drawn back. Musty tastes or earthy smells This may originate from microbiological growth either in the distribution system or within an internal plumbing system where water is left stagnant after periods of non-use. Some jointing compounds used for domestic fittings such as taps, filters and softeners or appliances can provide the right conditions to give rise to problems with taste. You can also experience musty taste when cold water pipes pass near unlagged hot water pipes or radiators where they can become warm. Running your tap for a couple of minutes will bring fresh cold water through. Metallic tastes Water is an extremely good solvent and has a natural tendency to dissolve or corrode metals and other materials. The extent of this problem depends on many factors including temperature, type of materials and the mineral balance of the water. Metallic tastes are associated with the internal plumbing and may be caused by new plumbing, mixed metals in the pipes which have been wrongly fitted or corrosion of pipes. Plumbing metals in domestic pipes made of iron, copper or zinc can corrode over time. This may cause a metallic taste which can be avoided by running the tap briefly if the water has been standing in the pipes overnight. Petrol/diesel/solvent/polish smell When the pipe connecting your property to the water main in the street is made of plastic (typically black alkathene or blue MDPE) and there is a chemical spill on your garden or driveway from products like heating oil, petrol, diesel or creosote, then these can rapidly soak through and penetrate plastic water pipes. These can cause unpleasant tastes and odours. Once the soil and plastic pipe become contaminated in this way, the only solution is to completely replace the pipe with either a metal or barrier pipe system. If you become aware of an unusual taste or odour following a chemical or fuel spill, then please contact us immediately.

6 Discoloured Water The water we supply is clean, fresh and of high quality but during its journey from our works to your taps it can be affected by a number of factors. Brown/Black/Orange appearance Brown water is indicative of iron in the water, usually from iron deposits in the water mains which, when disturbed, can discolour the water. Iron in water does not present any health concerns and is generally part of a regular diet. Most complaints about discoloured water are due to a change in the flow or pressure in water pipes, such as a burst main or where the fire brigades use the hydrant, which dislodges iron or manganese deposits which naturally build up in the mains. This can temporarily turn the water brown or black, although it is not harmful to health. Under normal conditions, these deposits do not affect the quality of the water. If we are working on our mains and think this may happen we take measures such as flushing the pipe to minimise the risk of discolouration. Occasionally the condition of the pipe connecting the property to the water main can also be the cause of discolouration. Some older properties may have galvanised pipework which connects to, or is within, the property. Over time this may corrode and if left to deteriorate may cause discolouration. If you experience brown water you should run your tap until it is clear again. If the water does not clear after approximately 30 minutes, please contact us for advice. From time to time, iron can discolour your laundry. If this happens, firstly check that your mains water is clear, and then re-wash your clothes after following a few simple tips: Keep the clothes damp and run the tap until the water runs clear. Use a synthetic detergent rather than a natural soap. Do not add bleach. Do not boil clothes. Rinse clothes by hand. Blue/Green water Copper water pipes are sometimes affected by corrosion and the by-products that are released can cause staining of fittings or a metallic taste to the water supply. If the water coming out of your cold water taps has a blue-green tinge or experience blue or blue-green stains below the taps on sinks or baths, then you may have copper corrosion in your pipes. This is more noticeable after the water has been standing in the pipes for some time. If you are concerned, then consider contacting your plumber.

7 White Water Drinking water which appears cloudy or white is usually caused by air bubbles, which are harmless and will disappear if the water is left to stand. This can be caused when air enters your domestic plumbing through a fault or following a burst main repair. If you leave the water to stand in a glass you will see the bubbles rise slowly to the surface and the water clears from the bottom upwards this air will eventually clear. Hardness and scale All water contains natural minerals such as calcium and magnesium. Without these elements water would taste flat and unappetising, similar to drinking distilled water. South East Water abstracts 75% of the water it treats from underground sources, very similar to the type of sources most bottled water comes from. The remainder is abstracted from rivers and reservoirs. Why is my water hard? All waters contain dissolved minerals which are absorbed by the water as it passes through or over the ground. The geological nature of the area from which the water is extracted for treatment and supply, reflects in the hardness of the water. The salts of calcium and magnesium form water hardness. Their presence in the water does not affect the wholesomeness of the water. Hard water is obtained when the water passes through or over limestone or chalk areas as it can readily dissolve the salts. Soft water is normally found in granite and sandstone areas, as the water absorbs very little in the way of hardness. Water from surface sources such as rivers and reservoirs are also softer. The level of hardness in water does not change very much, although its effects may be more noticeable due to new designs in kettles and the more common use of steam irons. What are the white bits in my water? The formation of scale is a natural characteristic of any water when boiled but more evident in harder waters; the temporary hardness salts of calcium and magnesium fall out of solution and form a scale (a chalky type deposit). This scale can attach itself to kettle elements. In the case of modern polypropylene ( plastic-type ) kettles, which are non-stick, the scale will float in, or on the surface of the water - this is not harmful to health. Inhibitors, conditioners and softeners There are a number of products available which either slow down the scale formation, act to reduce the formation of limescale or actively soften the water. These products work through a combination of chemically slowing down or removing limescale from the mains water. For water softeners always make sure that there is a supply of un-softened water coming into your home for drinking purposes.

8 South East Water is committed to supplying drinking water of the highest quality to all its customers both domestic and industrial. The need to alter the hardness of water, if at all, would vary from customer to customer. Some would want less but others would need a high level of hardness. Rather than interfere with the natural hardness of the region s water, we leave it up to the customer to decide whether artificial softening is the right choice for them. It has been found that hard water gives better protection against heart disease than softer water, which is why there is no requirement for a water company to soften their water supply. Lead Since the 1970 s, the use of lead as a material for water pipes has been phased out and lead solder has also been banned for use with copper drinking water installations. Consequently the level of lead allowable in drinking water has been reduced from 50 µg/l (micrograms per litre or part per billion) to 25 µg/l which is the current standard. This standard is to be reduced in the future to 10 µg/l by The only other source of lead in drinking water in some buildings is fittings made from brass. The extent of lead pick up depends on various factors; temperature, acidity (ph), water hardness, the length of pipe and the time that water is left to stand in the pipe (stagnation) before it is drawn off. Lead can build up in the body and it can be harmful. It is sensible to avoid excessive exposure from any source and it is therefore important to keep lead levels in water as low as possible. There are two options. You can either replace your lead pipes with other materials such as copper or plastic or follow some simple precautions to minimise your exposure to lead in drinking water. This includes: Do not drink water that has been standing in pipes for long periods, for example, overnight or if no one has been in for several hours. Run at least a washing up bowl of water off and use on the garden or for something other than drinking or cooking. If the length of lead pipes exceeds 40 metres, more than a bowlful of water will need to be drawn off. This need not be wasted but can be used on the garden.

9 Do not drink from bathroom taps. If you are unsure, you can make a simple check: Inside your home Look in or behind the cupboards in your kitchen. You may also need to look in other places, e.g. the cupboard under the stairs. Find the pipe leading to the kitchen tap. Check if it is lead along as much of its length as possible. Unpainted lead pipes are dull grey. They are also soft. If you scrape the surface gently with a knife, you will see the shiny, silver coloured metal beneath. Outside your home Open the flap of the stop valve outside your property. Examine the pipe leading from the stop valve to the property. If you can, scrape its surface gently with a knife. It may not be possible to do this in some cases as access may be difficult. Where can I get further advice? From your Local Authority Environmental Health Officer. From a qualified plumber such as one registered with the Institute of Plumbing, or approved by your water company. If you have lead plumbing and replace it, then South East Water will also replace any lead pipework between the main and your meter/stopcock. Remember the above is a guide only. If you have any further concerns, please do not hesitate to contact us, all contact details are shown on the back page of this leaflet.

10 Fluoride At present South East Water does not add fluoride to the water of any area it supplies. However, fluoride does occur naturally at trace levels in some of the sources used by South East Water. A bill voted on by MPs in November 2003 gave the decision on whether to dose water supplies with fluoride to the local health authority, working in partnership with local water companies and customer liaison groups. Should you require information on the levels of fluoride in drinking water all contact details are shown on the back page of this leaflet. Microbiology South East Water has a legal requirement under the Water Supply (Water Quality) Regulations 2000 as (amended 2007), to take random microbiological samples from its customers taps. The frequency and types of sample taken annually are dictated by the population area (zone) supplied by the company. Microbiological samples are taken for coliform bacteria. These are used as indicators of the microbiological quality of drinking water at our customers taps. We test for two groups of coliform bacteria: Total Coliforms These bacteria are a collection of relatively harmless micro-organisms that are widespread in the environment. They are non-faecal in origin and can exist in untreated water. Their detection is used as a basic indicator of drinking water quality. The Water Supply (Water Quality) Regulations 2000 standard requires an absence of Total Coliforms in drinking water. Escherichia Coliform (E.Coli) These bacteria, also known as thermotolerant or faecal coliforms, are an indication of contamination. They are widely present in untreated surface waters and soils subject to contamination from human, animal or avian faecal matter. They are monitored as an indication of the effectiveness of water treatment processes. The Water Supply (Water Quality) Regulations 2000 standard requires an absence of Escherichia Coliform in drinking water. Should Total Coliforms or Escherichia Coliforms be detected in any sample taken from a customers tap, South East Water immediately initiates procedures for the re-sampling and investigation of such samples. In the majority of cases, microbiological failures at consumer s taps are associated with plumbing devices attached to the taps. These fittings can harbour bacteria and prevent good tap hygiene.

11 Colony counts Colony counts are bacteria growing at 37 C and 22 C which enable a count to be determined of the heterotrophic bacterial population of the water. Heterotrophic bacteria are bacteria which are part of the normal ecology of the human body and are not a risk to human health. They commonly occur throughout the environment including water.the bacteria recovered in the colony count at 22 C generally represent those bacteria naturally present in water and are not of sanitary significance and thus have limited public health significance. Colony counts at 37 C, when compared with those at 22 C can be a useful quality indicator as they provide an early indication of a significant deterioration in quality. These counts are effective to assess the cleanliness and integrity of our distribution systems especially when there is an increase in the counts as compared to those normally recorded for a supply. These non-harmful bacteria may at times, impart an unpleasant taste to the water. Should you require any further information on any of the above subjects please do not hesitate to contact us, all contact details are shown on the back page of this leaflet.