The Facts About Water Treatment

Find out more about specific water problems

DO I NEED IT?
If you are using a water source other than mains, the answer is almost certainly yes. No matter that these supplies may have been in use for hundreds of years, there can be no guarantee that with such a variable quantity as natural water it will be safe at all times to all people. This is recognised by the enactment of current EU. legislation which demands a high degree of purity for all drinking water supplies. Put simply, the Environmental Health Departments will require your supply to meet stringent conditions, and if it does not do so, there is no option but to install water treatment or discontinue the supply.

This may seem heavy handed, but there is ample evidence that many cases of infections, often apparently trivial, occasionally not, are caused by drinking suspect water, particularly in the case of infants.

WHAT MAY BE THE PROBLEM?
Rain water may have absorbed contaminents from the atmosphere even before it reaches the ground. It may then pick up bacteria and indeed in grazed areas it is almost certain to do so. Water which percolates down through the ground, then absorbs minerals, typically iron and manganese, which may give an unpleasant taste, and cause problems of staining of laundry or baths etc. Calcium and magnesium may be present giving a hard water with the well known problems of washing and furring up of pipes. Acid water, typically in peaty areas can be corrosive, particularly to copper piping, producing staining and potentially being a health hazard. In addition to these health hazards, less seriously, but just as unpleasantly, natural water may be dirty, coloured, or smelly.

SO WHAT CAN BE DONE?
There are few supplies which cannot be treated effectively. However, there is no single treatment which is effective in all instances, and it is essential that the treatment used is appropriate to the specific application.

Find out more about specific water problems

HOW TO DO IT?
The first step is to have a site survey and a sample of the water analysed. Since water is a variable quantity and your supply is likely to vary from time to time, then preferably a number of samples should be obtained under different conditions, typically during dry and wet spells. This analysis will then form the basis of the treatment recommendations.

You may arrange the analysis yourself via any suitable analytical chemist (look under Yellow Pages) or your local authority may do the analysis for you. To determine how the necessary equipment will then be used in your instance, a site survey is necessary to ensure that the appropriate flows and pressures can be obtained. It is likely that water treatment will require a pump and the associated controls, and this is often the best purchasing route. Marshalls have been involved in pumped water supplies over a number of years, and the addition of water treatment to this service has been a logical and successful development. If there is one golden rule, it is never play a hunch or be persuaded that any item of equipment used in water treatment is right for your application without a proper analysis first. Invariably this will lead to a series of expensive mistakes.

WHAT AM I LIKELY TO NEED?
The most likely contaminent in raw water supply, particularly if it is collected from ground level, is bacteria. The more common means of sterilising water are chlorination, the use of impregnated filters, Reverse Osmosis (RO) and radiation by Ultra Violet (U.V.) light.

On a domestic or small commercial installation (licensed premises, restaurants etc.) the latter is rightly the most popular, and the effectiveness and simplicity of this method is well proven. The other methods have their advantages however and may be preferred from time to time, for instance chlorination in the case of high flows, or in the use of filters where no electrial power is available.

If pre-treatment is necessary, the equipment used will depend entirely on the result of the raw water analysis, but usually the treatment consists of passing the raw water through cylinders or filters containing various media. These are generally for the removal of minerals. In the case of a dirty water supply, some kind of pre-filter may be necessary, perhaps a backwash sand filter as is common on swimming pools. Taste, odour or colour can also be removed by backwash filters containing carbon. Should the raw water be unusually acid or alkaline, treatment will be necessary to correct this and usually this can be done by an appropriate filter, but occasionally dosing with a correcting chemical may be necessary using a dosing pump.

The above equipment is directly concerned with water treatment, but the likelihood is that insufficient pressure will be available to pass the raw water supply through this equipment, and so it will often be necessary to use a pump together with control equipment. This will give a completely automatic pressurised supply operated simply by opening any tap in the system.

WHERE WILL IT FIT?
If sterilising is all that is necessary, the common U.V. filters are compact enough to fit under a sink or in a kitchen unit etc. However, maintenance will be required from time to time and it is in everyone's interest to keep the equipment accessible. Pre-treatment may require a vertical cylinder(s) measuring approximately 1m high x 250cm dia.

It is preferable in this case to mount the equipment package (which may require a total floor area of around 1 metre square) in a shed, lean-to or perhaps a cellar. Maintenance will be required from time to time, and this will invariably involve the spillage of water, so provision must be made for this.

WHAT WILL IT COST?
Only a site survey will properly answer the question, but as a guide, the simplest installation of a U.V. unit and filter will cost around £500, and a comprehesive package including pre-treatment and water pressure booster pump and controls will range to around £3000. In certain instances, grant aid is available, and this should be explored with your local authority.

WHAT ARE THE BENEFITS?
The obvious benefit is that you will have a completely sterile, clean, and taste-free water supply without the cost of connecting to a public supply main and heavy annual water rates. The equipment is long lived and an asset which will enhance the value and saleability of your property. Indeed, it is unlikely that mortgages will be offered for properties with untreated raw water supplies.

Where a pumped supply is being installed (and this will be in most instances) there is the additional advantage that greatly increased pressure will be available throughout the system giving improved flows and perhaps enabling the use of domestic appliances which require higher pressures (some washing machines, dishwashers etc). Using a pumped system means that the raw water header tank is eliminated, and with it an obvious source of contamination both by dirt and bacteria, and also a potential freezing hazard.

HOW DO I FIND OUT MORE?
This fact sheet is intended to give a brief background and explanation of water treatment for raw water supplies. Where we are submitting a quotation, we will give full information on the equipment proposed, and the manufacturers literature may be included with our proposals.

If you wish to find out more, contact our sales team on 0161 609 8888 who will be happy to help.