SWIMMING POOLS

Evening Post, Volume CXXII, Issue 106, 31 October 1936, Page 14

SWIMMING POOLS

MODERN BATHS

PROTECTING HEALTH

SAFETY FACTORS

The lack of tepid swimming baths in Wellington has been given prominence in the election campaign proceeding at the present time, and one candidate has suggested baths as part of an Exhibition scheme for 1940. If such baths are to be built the most modern devices for sanitation and safety will be required to make them really popular, and in this respect a paper on sanitation and safety read by Dr. Hamilton Montgomery at one of : the staff meetings of the Mayo Clinic, Rochester, Minnesota, U.S.A., is of interest.

To build a modern outdoor swimming pool one should have the advice and assistance of an architect, a construction engineer, an expert on filtration equipment and purification of water supply, a public health official, and various physicians, he states, especially a bacteriologist, an ophthalmologist, an ear and throat specialist, and a dermatologist. Having secured the value, of the knowledge of these it is still important to find a suitable site for the pool as proper soil and sub-soil are required for a foundation. ANTIQUATED POOLS. < "The antiquated swimming pool of the nineties," Dr. Montgomery writes, "with its dingy wooden bathhouse and lack of ■ sanitation and of means ,of ■purification of the water, was justly j condemned because of the many ! respiratory, gastro-intestinal, and cutaneous infections acquired tbei'efrom. The old swimming holes and beaches then usually were preferred as places in which to swim. Even today such places can be made relatively sanitary by the addition of gravel to the bottoms and by dragging through the swimming areas daily chemicals containing chlorine, and sometimes in addition ammonia and copper sulphate."

The next era, he continues, was the concrete swimming pools which were drained at intervals or had a constant stream of water running through them, but such methods required an abundant supply of water, and it was difficult to maintain an equal distribution of chlorine. If used to excess the chlorine would cause smarting of the eyes. The idea of the modern swimming pool developed from a study of conditions made in 1918. MODERN SANITATION. "Sanitation of the modern concrete or tile swimming pool is based on the same principles as purification of the supply of drinking water for cities which have a water supply that is originally polluted," he states. ■ "It applies equally well to indoor and outdoor pools and to pools varying in capacity from less than 50,000 to almost 2,000,000 gallons of water. The water is purified by passing through a set of pressure filters or gravity filter tanks and being treated with chlorine and ammonia in proper amounts. . . .

The Rochester pool is 165 ft by 100 ft with an additional diving area of 25ft by 50ft, and holds 570,000 gallons of water. ' The city water, which fulfils drinking water standards, comes into the pool through a surge or supply tank; there is a drop, or gap, to prevent any water from the pool backing up into the city water mains. Because of a similar device water cannot back up from sewer connections >or from toilets into the swimming pool or the .filters, thus avoiding any possibility of an outbreak of amebic dysentry such as occurred in one of the larger cities recently because of faulty plumbing.;:

"Once the water is in the pool, rfecirculation is as follows: Water is withdrawn from multiple outlets at the deep end of the pool and passes through a hair and lint catcher; the proper amount of chlorine is added and then definite amounts of alum and soda ash, after which the water goes through the circulating pump. The water next passes through pressure filters and proper amounts of ammonia are added. The water then flows into the pool at the shallow sides, through eleven inlets.' A uniform distribution is obtained throughout the pool, and 1200 gallons of water are recirciilated every minute, or the entire contents of the pool every eight hours. The amounts of chlorine and ammonia are controlled by accurate instruments identical with those -used for the purification of city water supplies. At intervals, depending on the load in the pool and other factors, the filters are backwashed, and this dirty, polluted water goes into'the sewer. UNDERWATER VACUUM CLEANER. Dirt and foreign particles deposited on the bottom of the pool are cleaned out by means of a vacuum cleaner which works under water. Particles which float on top of the water usually drift to one side, and can be removed by a screen or muslin rake or by causing the water to overflow into the scum gutters. The daily loss.of water by backwashing, cleaning, and evaporation amount to 5 to 8 per cent, of the pool's total capacity. More than 0.5 parts of chlorine per million of water are usually found to be irritating to the eyes, Dr. Montgomery states, although in many instances the acidity of the water and not the chlorine has caused eye trouble. In 1929 it was,found that the addition of ammonia to water which had been treated with chlorine resulted in the formation of chloramine, which did not irritate the eyes, and this also made the chlorine more stable in pools exposed to the sun. A fence around the pool is an important safety factor, Dr. Montgomery states, but underwater lighting is even more important, because overhead lighting would not penetrate more than- five- or 'six feet if the water was roughened by swimmers.