Mr. Carruthers agreed with Mr. Wallace that the main duty of sewers was to carry away the dirty water from the houses after it had been fouled by mixture with household slops. The water-closet dejecta were of far less importance. Their addition to the sewage did not materially increase the foulness of the latter, as was shown by the fact that the sewage of water-closeted towns was not perceptibly different from that of towns where middens or cesspits were used. He would recommend the use of water-closets as cleaner than earth-closets, and thought it was straining out a gnat and swallowing a camel to allow the ninety-nine parts of nastiness included in the household slops to enter the sewers, and then to go to great trouble and expense in order to keep out of them the one part which is included in the water-closet dejecta. He would also allow rain-water to enter the sewers. He did not believe in the separate system. If the rain was not admitted, no amount of flushing which they were likely to get would keep the sewers clear; and a town with sewers from which the rain was excluded would be far more unhealthy than if it had no sewers at all. The cost of making the sewers large enough to carry rain as well as sewage was not great, as it is necessary to make sewers of such size that, when running full, the sewage will have such velocity that solid matters would be carried along, and, when great inclinations are not procurable, sewers of the requisite size to effect this would also carry ordinary rainfall. He thought the best thing to do with the sewage would be to throw it into the sea; it would not create any great nuisance in the case of large towns if it was taken some distance below low-water mark.
Mr. O'Neill was also in favour of the combined system of draining all into the sea. The storage of such a manure had in most cases proved a failure; it did not pay. He was inclined to think that the use of salt water would do more harm than good. Mr. Dyer's plan of cartage would not answer. He read extracts to show that, according to Sir J. Hawkshaw, it was too complicated a system to work well. He did not agree with Mr. Campbell's pail system except on a small scale, and he was of opinion that nothing but the main-drain system would succeed.
Mr. Frankland said that a system like Mr. Dyer's was worked in Switzerland, at Zurich, but the scavenging proved very offensive.
Mr. Higginson thought the earth-system objectionable where water can be obtained. Mr. Campbell's plan might do for separate houses, but not for towns. He believed in the combined system of carrying everything into the sea. The outfall should be fixed in such a position as would guard against the sewage being returned by the tide. There should be good ventilation, plenty of air-holes, and especial care should be taken in laying and trapping house-drains.
Mr. J. Young did not agree with what had been said against the earth-closet. He objected to the plan of discharging into the sea. He thought it would be unwise to throw away such a valuable manure. He quoted Professor Levy in support of what he said.
Mr. Maxwell said that, whatever plan was adopted for Wellington, it would be well that the Municipal body should have full power to carry out the system.
Dr. Newman thought that almost all towns required the separate system, and the earth-closet was found to work well and give no offence. He also thought the main-drainage system would not work, and that the discharging into the sea was highly objectionable, and would pollute the harbour, as it had done at Sydney. No one seemed to notice anything about the drainage of the subsoil, which would have to be taken away. He considered that large sewers were in danger of breakage from the effects of earthquakes, while pipes would not be so.
