The Gelligaer Area came under the Merthyr Rural Sanitary Authority.
As with the situation of the water supply, there did not seem to be a structured system with regard to the disposal of waste and, during June 1875 notices were served on various Fochriw residents to “abate nuisances” at the backs of their properties. However, what appeared to be an official ash-pit at the front of John Harris’s house, who was the station master at Fochriw, led him to write to the Board complaining of its nuisance and requesting its removal, to which two Board members strongly objected. Board members paid a visit to certain streets and found to their satisfaction that sanitary conditions had greatly improved
Scavenging licences were issued to John Matthews as follows. 1879 – 5s a week, 1880 – 10s a week, 1882 - £27. 1887 to Evan Kinsey at 7s.9p. per week.
During April 1880 it was reported that there were pigeries at the rear of Guest Street that were in a filthy state and their removal was recommended, also, that there were eight houses to the south of Guest Street which had no “privies”
During August 1885, the Board discussed the urgent need for a drainage system for Fochriw which, it transpired, had been discussed previously but did not proceed due to difficulties in obtaining the required land. It was stated that a Local Board should be formed for Gelligaer and then they would have the powers to purchase the land compulsorily. It would appear that by the following month the Gelligaer Rural Sanitary Board was in being.
During March 1898 an inquiry was carried out regarding the purchase of land for a sewerage scheme at Fochriw and it would appear that by the following month a sewage tank and Works had been installed since the Council advertised for a man to look after the installation, together with the water supply and the lighting of public lamps at Pentwyn and Fochriw, at 24s per week.
Approximate site of first sewage works - Google Earth link
However, all was not well, and during October 1900, a public meeting was held at Fochriw which resulted in a resolution being passed that requested a thorough sanitary inspection of Pentwyn and Fochriw, together with the employment of additional sanitary inspectors in an effort to improve conditions, especially since many families had suffered severely from the Fever. This must have had the desired effect since, on 16 January 1902, a contract was awarded in the sum of £861.6s to Felix Davies & Co of Bargoed for the installation of a sewerage system.
Between 1923 and 1927 the Council constructed main sewers to serve the Cylla and Darran Valleys, connecting to the Sewerage Board's trunk sewer. The cost of these was £47,000. The last stage in the sewerage of the district was reached in 1953 when the sewage works serving Bedlinog were abandoned and a new sewer provided to connect to the trunk sewer of Merthyr Corporation at Quaker's Yard.
At Fochriw, the initial sewage treatment works was located in what is now the allotments and, as the village grew, it was relocated to a field on the western side of the brook just below the southern end of the football field underneath what are now the back gardens of the top end of Glan-y-Nant.