Sir—In accordance with your instructions to me, dated 6th inst., I have the honour to report on the quality of the Dunedin Water Company's water. Three of the .samples examined, marked A, B, C, in the subjoined table, were delivered at the Laboratory by one of your officers. The sample marked D, I collected at the Laboratory tap here. As my Report to you, dated 30th, June of last year, exhibits the results of a careful and exhaustive analysis of the water supplied to Dunedin at that time, I have not considered it necessary to do more at present than determine the proportion of total solid residue left on evaporation, and the proportion of organic matter in the several samples. The table subjoined shows the results I obtained under these two headings on the 9th of the present month, also the results obtained on the 25th of June of last year; and, for comparison, I have transferred from Watts' Dictionary of Chemistry corresponding results similarly obtained from river and lake waters supplied to London and other communities in various parts of Europe.

It will be seen from these results, that the water taken from the Corporation Offices' tap last week contains about 36 per cent, more organic matter than water taken from the same tap in last June. This increase of organic matter is probably to be accounted for by the circumstance that the present analysis was made at an earlier period of the year, before the cold weather has set in, and before the heavy rains of winter have swept away the looser vegetable growths.

Under the microscope (Nachet's, 400 diam.) the water taken from the Corporation and Laboratory taps does not show organisms in greater variety or in much greater proportion than I observed in June last.

The sample submitted from the Upper Reservoir, however, shows low cellular growth—confervæ, desmids, diatoms, &c.—in such abundance as to render that water, in its present condition, in my opinion, quite unfit for domestic use. In view of these results, showing so large an increase of organic matter, the water will not quite maintain the good character I was able to give it in my last Report. Though still within the limits of water extensively used for domestic purposes, it is, I think, desirable that something were done to improve its quality. A great improvement could be easily effected by causing the water to undergo, before entering the main, a process of filtration, either through a bed of sand and gravel, or these mixed with clay and powdered charcoal. By this means, the suspended impurities—vegetable growths, particles of clay, and the débris of plants—would be removed; and if charcoal were used, the dissolved organic impurities also to some extent.

If, in addition to some such process of filtration, the water were caused to flow for a few miles in the open air over a sandy or pebbly channel, so as to be exposed to the action of light and the oxydising influence of the atmosphere, it would rank, for domestic purposes, among the best waters supplied to any community.