|Category||Local government district|
|Location||England and Wales and Ireland|
|Created by||Public Health Act 1873|
|Public Health Act 1875|
|Public Health (Ireland) Act 1878|
|Created||England & Wales 1875|
|Abolished by||Local Government Act 1894|
|Local Government (Ireland) Act 1898|
|Abolished||England & Wales 1894|
- Urban sanitary districts in towns with existing local government bodies
- Rural sanitary districts in the remaining rural areas of poor law unions.
In England and Wales, both rural and urban sanitary districts were replaced in 1894 by the Local Government Act 1894 by the more general rural districts and urban districts. A similar reform was carried out in Ireland in 1899 by the Local Government (Ireland) Act 1898.
 England and Wales
Urban sanitary districts were formed in any municipal borough governed under the Municipal Corporations Act 1835, in any Improvement Commissioners District formed by private act of parliament, and in any Local Government District formed under the Public Health Act 1848 or Local Government Act 1858.
The existing governing body of the town (municipal corporation, improvement commissioners or local board of health) was designated as the urban sanitary authority.
When sanitary districts were formed there were approximately 225 boroughs, 575 local government districts and 50 improvement commissioners districts designated as urban sanitary districts. Over the next nineteen years the number changed: more urban sanitary districts were formed as towns adopted legislation forming local boards and as additional boroughs were incorporated; over the same period numerous urban sanitary districts were absorbed into expanding boroughs.
Rural sanitary districts were formed in all areas without a town government. They followed the boundaries of existing poor law unions formed in 1837, less the areas of urban sanitary districts. Any subsequent change in the area of the union also changed the sanitary district. At the time of abolition in 1894, there were 572 rural sanitary districts.
The rural sanitary authority consisted of the existing poor law guardians for the rural parishes involved.
The Local Government Act 1894 brought an end to sanitary districts in England and Wales. In boroughs, the sanitary authority was merged into the corporation. All other urban sanitary districts were renamed as urban districts, governed by an urban district council. Rural sanitary districts were replaced by rural districts, for the first time with a directly elected council. It was a requirement that whenever possible a rural district should be within a single administrative county, which led to many districts being split into smaller areas along county lines. A few rural districts with parishes in two or three different counties persisted until the 1930s.
A system of sanitary districts was established in Ireland by the Public Health (Ireland) Act 1878, modelled on that in England and Wales.
Urban sanitary districts were established in the following categories of towns:
- The City of Dublin
- Boroughs governed under the Municipal Corporations (Ireland) Act 1840
- Towns having Town Commissioners and a population exceeding 6,000
- Townships with Town Commissioners under private acts of parliament
The existing corporation or commissioners became the urban sanitary authority. The Local Government Board of Ireland, created by the same act, could designate other towns with commissioners as urban sanitary districts.
Rural sanitary districts were formed in the same way as those in England and Wales, and with similar rural sanitary authorities.
The sanitary districts were abolished in 1899, under the Local Government (Ireland) Act 1898, being merged in boroughs, or forming urban and rural districts. A large number of the rural sanitary districts were broken up into smaller rural districts along county lines, often taking the name of the sanitary district followed by a number - for instance, Ballyshannon rural sanitary district was split into Ballyshannon No. 1, Ballyshannon No. 2 and Ballyshannon No. 3 rural districts in Counties Donegal, Fermanagh and Leitrim respectively.
Sanitary districts were not formed in Scotland. By the Public Health (Scotland) Act 1867 public health duties were given to the town councils, commissioners or trustees of burghs, and to parochial boards. In 1890 the public health duties of parochial boards were allocated to the newly created county councils, administered by district committees.
 See also
- List of sanitary districts in Buckinghamshire
- List of sanitary districts in Dorset
- List of sanitary districts in Middlesex
- Local Government Areas 1834 - 1945, V D Lipman, Oxford, 1949
- Guide to the Local Administrative Units of England (2 vols.) F A Youngs, London, 1991
- Public Health Act 1873 (35 & 36 Vict. c.79)
- Public Health Act 1875 (38 & 39 Vict. c.55)
- Public Health (Ireland) Act 1878 (41 & 42 Vict. c.52)