In the early part of the 20th century many towns in the UK were being connected to a mains water supply. Hayeswater Lake was considered a suitable supply of clean water for the market town of Penrith, some 20 miles to the north east.
A shallow dam was built and a 9 inch pipe laid from Hayeswater 'Reservoir' (once dammed) to Penrith in 1921. It was soon decided that the water needed to be filtered and suitable land was purchased by The Penrith Urban District Council in November 1926. The Vendor was Robinson Nawson Pattinson of Parcey House Hartsop.
Along with the freehold purchase of the land came a right to build a suitable building 'The Filter House' and the right of access from Hartsop over the private carriageway up to that freehold land. There were also obligations to erect and maintain a wall around the property and maintain in good order and condition that carriageway from Hartsop.
The stone building was erected in 1927. It was built with oversize windows and doors so as to appear like a small shed or cottage when viewed from afar. A small side extension was built on the north face in the 1980's for a toilet and washroom along with cesspit and drain-away for those working at The Filter House.
The National Trust planted a tree on 6th October 1902 to commemorate the first land owned by the trust in the Lake District https://www.nationaltrust.org.uk/borrowdale-and-derwent-water/trails/octavia-hill-walk-at-brandelhow-park-derwent-water .
The land to the south of Hayeswater Gill was acquired as a gift by the Trust in 1976 from Lake District Farm Estates Ltd.
Much of the land surrounding The Filter House was acquired by the National Trust in 1992 https://nationaltrust.maps.arcgis.com/apps/webappviewer/index.html?id=a7a56518c10845daab1950239e041447. Bought by the Trust with bequests from Mr R. J. H. D. Simpson and Miss E. A. Golding.
North West Water was responsible for the maintenance and upkeep of the water supply from Hayeswater Reservoir. The business was privatized in 1990 and merged with NORWEB in 1995 to create United Utilities, who remain responsible for the water supply in the North West.
However in the early 2000's the cost and utility of maintaining the Hayeswater supply was deemed to expensive. The supply was closed in 2004 and the damn removed from Hayeswater in 2005. The building sat abandoned for a number of years, but in 2008 it was decided to sell the freehold at auction. To this end all of the heavy plant was removed to leave an empty shell. The property was put to auction in December 2008 and sold for £100,000 to a private individual.
In 2009 a borehole was sunk for a private water supply to replace that utilized by the building before the removal of the plant. The building had full electrics, a phone line and a septic tank with soak-away. A shower was installed in the WC room. It was then used as a private camp house for the next 10 years.
Michael Brett acquired The Filter House in April 2020 with a view to sharing this magical location with others. Unfortunately the planners did not agree so it will have to stay as a private holiday home for the time being.