PURITY OF WATER

New Zealand Herald, Volume LXXII, Issue 22261, 8 November 1935, Page 19

PURITY OF WATER

FARM AND FACTORY SUPPLY INFLUENCE ON PRODUCTS WAIKATO AND HAURAKI AREAS In the present general move to secure higher quality dairy produce it is being revealed that more attention must be paid to both tho quantity and the quality of tho water used in dairy factories and on tho farms supplying them. As a foundation for more intensive work a reconnaissance has been made ot the water supplies of farms and factories in the Hamilton and Hauraki districts. The results have been published in bulletin form by tho Department of Scientific and Industrial Kesearch. This has been written by Mr. N. H. Taylor, of the Geological burV °ln an early chapter, tho bulletin treats generally with tho water requirements of farms and dairy factories, the large volumes of water required lor the cooling of milk on those farms that supply cheese and dried milk factories being' stressed. Tho need for water of a high bacterial standard and the difficulties attending tho use of mineralised waters are also discussed. The Hamilton Basin Although some account is given of the use of rain water and surface water in tho Hamilton district prominence is given to tho ground water, that is, water contained in strata below tho surface, as this is the chief source of supply on most farms. In order to understand the ground water conditions it is necessary to understand the ecology of the area. The Hamilton basin was formed by faulting movements in tho earth's crust and tho resulting depression was filled in by the rivers with beds composed of gravels, sand and clay. Beds of peat subsequently accumulated in tho swamy parts of the depression and were buried as the hllmLater this filling wns eroded into hills and valleys, a rolling lowland being formed. In comparatively recent times the Waikato River invaded tho area, and partly smothered the rolling lowland with a largo plain of sand and gravel. Tho low hills seen to-day rising from the plains near Hamilton are but the tops of tho ridges of the old rollinc lowland. Theso old buried ridges act as ground water dains and obstruct the flow of the ground water to tho rivers, thus producing in tho Waikato the unusual feature of a water table close to the surface even in areas adjacent to deeply-entrenched rivers. Tho general movement of the ground water is from south to north throughout most of the Waikato. Iron Impregnation Much of the ground water in the north and north-eastern parts of the basin is highly impregnated with iron. The difficulties attending the use ot such water are outlined, and evidence is collected to show that the use of such iron-bearing water may effect the quality of tho dairy produce. The temperature of the water m the wells visited ranged from 57 degrees F. to 75 degrees F. For cooling purposes water should bo below 60 degrees I*. In general the deeper the well the higher tho temperature, but this is not true in every case. Tho temperatures of many wells correspond roughly with a thermal gradient of 1 degree F. rise for every 50ft. t>f depth. ; In the Hauraki lowland the ground water conditions aro further complicated by the presence of deeply circulating supplies which rise below the plains, and minglo with the shallower waters. This water is not only warm, but is also mineralised and most of the wells in the Hauraki Plains tap waters of this type. Theso waters are useless for cooling purposes and because of their mineral content are generally undesirable for use on dairy farms. In the central and southern parts of Hauraki lowland the ground water conditions are similar to those of the Hamilton Basin and the same troubles with corrosive and iron-bearing waters are encountered. Improving the Supplies Tho chief defects in the present supplies seem to be: —(1) Tho absence on great many farms of adequate supplies ot low temperature water for cooling purposes. (2) The high iron content of many of tho waters. (3) Tho danger of pollution of many of tho supplies. In districts where suitable ground water cannot bo obtained more use should be made of rain water directly caught and of surface water. A district such as tho Hauraki Plains readily lends itself to tho reticulation of water from the adjacent upland. Suph schemes are viewed unfavourably by some because of the high temperature of many surface waters supplied to farms, and because tho charge for such water is in many places considered to be too high. Many surface waters supplied to farms have too high a temperature because the water is impounded in large open reservoirs and also because the conduit pipes are not buried. The excessive cost of such supplies as against the cost of using ground water, does not appear to be always borno out by figures and tho question of cost for any particular scheme can only be decided after a competent engineer has inspected the area. Need for Research Improvements are needed in the types of milk and cream coolers now in use on farms. If a cooler were devised the water pipes of which could be readily cleaned out, some of the difficulties attending the use of iron-bearing waters would disappear. A cheap electric refrigerator is also needed for use on farms where efficient 1 cooling by water is not possible. Dairy scientists agree that one of the chief causes of defects in our dairy produce is the multiplication of bacteria between the time of drawing off the milk from the cow and pasteurisation at the dairy factories. It tollows, therefore, that in dairying districts good supplies of pure cool water are essential to check tho deterioration so liable to occur in warm milk or cream. Ground water studies can assist in attaining these ends and should be actively pursued. At tho same time research is needed into the quantity and the quality of water used in dairying districts and into the effects which it exerts upon the quality of dairy produce. Until such work is put seriously in hand, much time will be spent in fruitless speculation.