Caribbean Disaster Mitigation Project
Implemented by the Organization of American States
Unit of Sustainable Development and Environment
for the USAID Office of Foreign Disaster Assistance and the Caribbean Regional Program

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Drawings to Accompany the Building Guidelines

Section F: Plumbing, Sanitation, Water Supply and Gas Installations

Introduction | Section A | Section B | Section C | Section D | Section E | Section F | Section G
Download AutoCAD DWG files (zip archive): Section A | Section B | Section C | Sections D-G

Figure F-1

Figure F-1: Schematic Drawing Showing Connection of Fixtures for a Single Storey Dwelling

The general arrangement for connection of fixtures to a single stack is depicted. It is important that no soil or waste pipes discharge into bends attached to a water closet (WC) bowl. The pipes must be laid to adequate falls to the service manhole.

 

Figure F-2

Figure F-2: Detail of Manhole Construction

Manholes are to be installed at every change of direction and gradient, spaced no more than 60 feet apart. Manholes are constructed of reinforced concrete or blockwork and the drain where it passes through the manhole shall be carried in an open benched channel. Manhole covers are typically of steel, cast iron or concrete and are to be airtight and fitted with lifting handles to facilitate removal.

 

Figure F-3

Figure F-3: Conventional Privy

Pit privies shall preferably be located on the leeward side of a building and shall be ventilated. Privies shall not be used in areas where the water table is within 2 feet of the surface since they will not function well. The precast concrete slab pit privy has been adopted by many health authorities.

There shall be openings at the top of the walls to dissipate odours. For maximum odour control a vent pipe can be installed in the tank to carry odours away from the privy. The vent pipe shall be at least 6.0 inches (150 mm) in diameter, painted black, screened with a wire gauze and located on the sunny side of the latrine so that air inside the pipe will heat up and create an up-draft. The pipe shall extend a minimum of 2 feet above the roof of the privy.

The door should open outwards to minimize the internal floor area.The toilet shall be sufficiently screened to discourage flies. The walls and roof shall be weatherproof, shall provide privacy, exclude vermin and be architecturally compatible in external appearance with the main house.

 

Figure F-4

Figure F-4: Details of Construction of Water Cistern

In areas without a public water supply, a water storage cistern should be constructed for each house or dwelling, along with a rainwater collection system from the roof or other suitable catchment. The size of a typical storage tank or cistern is as shown.

The water storage cistern can be located under one or more buildings of a dwelling group or consist of a separate tank remotely located. The cistern shall be located uphill and as far as practical from any septic tank, privy, soakaway, or leaching tile field. The water storage cistern shall be preferably reinforced concrete and provided with access hatches to allow cleaning out and repairs.

The cover of the water storage cistern shall be of a durable, non-rotting material. Wood or plywood is generally not satisfactory. The cover must be tightly fitting to prevent mosquito breeding. Light should be excluded from the cistern water to prevent the growth of algae. Sufficient overflows must be provided to prevent flooding of dwellings. The overflows must be screened to prevent the entrance of mosquitoes, frogs, or other vermin.

 

Figure F-5

Figure F-5: Standard Septic Tank Details

The basic function of a septic tank is to receive domestic sewage, partially treat it, segregate the solids, and discharge the liquid to a tile field or soakaway. Anaerobic bacterial action breaks down much of the solid matter into liquids and gases. While in an efficiently operating tank the liquid discharge is comparatively clear, tanks do not accomplish a high degree of bacteria removal and infectious agents including pathogenic organisms may be widespread in the effluent which is "septic".  The primary purpose of the tank is to condition sewage. To provide for maximum solids removal, adequate tank capacity is necessary.

 

Figure F-6

Figure F-6: Alternative Arrangements of Sanitary Fixtures in a Bathroom

Six different arrangements of small two- and three-fixture bathrooms are depicted. The dimensions shown are the minima for proper use of the spaces.

 

Figure F-7

Figure F-7: Typical Plumbing Layout for a Small House

All plumbing shall be installed in a workmanlike manner. The water supply pipes should be provided with a properly protected and easily accessible stop cock or gate valve near to the boundary.  The fixtures should be of smooth, hard, durable, impervious and corrosion-resistant materials, free from flaws and blemishes. All fixtures connected to foul drawings shall be trapped as close to the fixture as possible. The water closets shall have a vent pipe of not less than 1 inches in diameter. A drain laid under a floor on fill, must be laid in a straight line for its entire length beneath the building, and should not exceed 40 feet in length.

 

Figure F-8(a)

Figure F-8(a): Soak-Aways in Areas with a High Water Table

 

Figure F-8(b)

Figure F-8(b): Soak-Aways in Areas with a Low Water Table

Soakaways shall be used as alternatives to shallow absorption fields where sub-surface conditions are feasible. They shall never be used where there is likelihood of contaminating underground water supplies, such as areas with fresh water wells. The most suitable disposal system is dependant on the percolation rate and this is generally determined by the Public Health Authority.

In the construction of soakaways, proper precautions shall be taken to prevent the side walls from collapsing while workmen are in the hole.The soakaway pit is to be lined with stones, bricks, or concrete blocks laid up dry with open joints backed up with at least 3" of gravel. The bottom of the pit is to be filled with coarse gravel (pea rock), to depth of at least two feet. The cover is to be made of reinforced concrete or steel. Where two soakaways are to be constructed they shall be located not less than three times the largest of the surface dimensions apart. Soakaways may be used in all areas for the disposal of excess rainwater or run-off from buildings that is not of a septic nature.

Introduction | Section A | Section B | Section C | Section D | Section E | Section F | Section G

CDMP home page: http://www.oas.org/en/cdmp/ Project Contacts Page Last Updated: 20 April 2001