Annual report of the Public Health Department / Zanzibar Protectorate.

  • Zanzibar. Public Health Department.
Date:
[1917]
Catalogue details

Licence: Public Domain Mark

Credit: Annual report of the Public Health Department / Zanzibar Protectorate. Source: Wellcome Collection.

    6/50 (page 4)
    only to be seen to be condemned and emphasise the urgent need for a properly constructed sewerage system for the town. Many of these drains discharge into the Creek, the foul contents trickling out to be distributed over the sides of the Creek by the rising tide and only partially removed as the tide ebbs, a stinking morass remaining during the hours of low water. Some improvement undoubtedly may be expected from filling in the sides of the Creek and grading them to a central cement channel but under no circumstances will such a channel be suitable for dealing with sewage, it being impossible to secure an adequate fall. Other drains discharge on to the beach of the roadstead. These are less objectionable but they are constantly becoming silted up with sand and complaints are frequent. I believe it would be possible to connect up the greater part of the town proper, if not the whole of it, excluding the ’Ngambo dis¬ trict, to a main sewer outlet or reservoir at Shangani point capable of holding the total sewage of 6 hours and discharging into deep water on the ebbing tide. Such an arrangment as this would enable adequate fall to be given by taking advantage of the 15 feet rise and fall of tide. Although the installation of water carriage of sewage is not feasible until a further water supply has been obtained it would be Avell if the engineering problems could be considered and solved in anticipation of that event. Cesspools.—With the exception of the few drains referred to in the last paragraph and the one or two properly constructed drains to the sea from European residences on the sea front, cesspools are the accepted means of disposing of household waste water from baths, kitchens, etc., and the whole town proper is literally honeycombed with these and the equally universal “choo” or privy pit. Owing to the extraordinary porosity of the soil and sub-soil many of these cesspools have been receiving large quantities of liquid daily for years without the necessity for their being emptied arising. For this reason, so long as it is recognised that the sub-soil is already thoroughly foul and that the wells are polluted and unfit to be used except perhaps for washing purposes, properly constructed cesspools may be considered far preferable to the existing bad drains. It must however be remembered that all parts of the town area are not equal¬ ly fortunate as regards a porous sub-soil and it is found in certain places that the cesspools require to be emptied with great frequency. The importance of cesspools as breeding places for Culicine mosquitoes, Culex fatigans in particular, has been pointed out in previous reports and the advantages to be expected from inserting some form of S or U or yard gully trap at all cesspool inlets was mentioned by Dr. Curwen in his report for 1916. During the year a certain number of these gully traps have been fixed but unless these traps are placed in such a position as to be readily inspected and kept clean they are likely to cause a worse nuisance than the original cesspool. It has been impossible to obtain many of these