Engine House, Thames Water Station

The Engine House at Thames Water Station, built in 1896, is designed in a classical style. It is constructed of stock brick with red brick dressings and terracotta embellishments. While the original roof was likely slate, it has been replaced with roofing felt. The building features a plan with two parallel ranges. The larger range has a curved pediment adorned with an elaborate terracotta design that includes the inscription "New river Grand Junction Staines reservoirs West Middlesex incorporated 1896." To the left of the pediment is a roundel depicting a factory, and a shield featuring a standing youth in Grecian dress. On the right side, there is another roundel showing an old man and a young woman, also in Grecian attire.

The building has a corbelled cornice and a central projecting porch with a panelled parapet and a round-headed arch supported by impost blocks. It features four chambered casements topped with a round-headed grading and flanked by brick pilasters. The side elevation includes ten windows, with central and end pairs set in projecting arches that have panelled or balustraded parapets above. These windows have cumbered heads, while the other windows are round-headed and located under a corbelled cornice, separated by pilasters. Attached to the side is a smaller wing that matches the main style, featuring a curved pediment at one end with two terracotta roundels and three windows. The internal machinery dates from the 20th century.