Located at the eastern end of Queen Street in the Beach neighbourhood, this Art Deco masterpiece was constructed in two phases, the first west portion between 1932 and 1941, which included half of the Filtration Building and the second between 1950 and 1952 when the Filter Galleries were doubled to their current size. Designed by architect Thomas Pomphrey (along with the engineering firm Gore & Storrie Ltd.), the facility is a striking example of how civic architecture can be both functional and inspiring. Named after the Works Commissioner of the day, Rowland Caldwell Harris, the plant and its grounds are a Toronto landmark, designated under the Ontario Heritage Act. The Plant along with Harris' other engineering gift to the City, the Bloor Viaduct, figured prominently in Michael Ondaatje's novel 'The Skin of a Lion'.

Over the last few years a major restoration has been taking place, including masonry and roofing replacement, to ensure that the plant continues to perform as the key component in the city's delivery system for fresh, clean water, besides looking great for its additional sideline work. On the downside, new security measures have had to be accommodated in modifying the design of the grounds of the facility.

Part of the project has involved the replacement of the copper roof and skylights over the grand Filter Gallery that spans from one end of the main Filtration Building to the other. As well, due to the age and state of the structure, a number of steps needed to be taken in replacing various wood battens, and sections of the skylight framing system, primarily because of mishandled detailing for the control of condensation in the original construction. Complicating the project was the difference in detailing between the western wing and the eastern one, which was completed at a later date. A new lightning protection system using exterior copper braiding was installed to protect newly installed digital monitoring equipment for the treatment process.

Creating a uniform installation that would address these issues fell to Taylor Hazel Architects (lead architects Charles Hazell and Mark Wronski, with the assistance of Read Jones Christoffersen Ltd. Engineers and Day Behm Engineering Ltd. (lightning protection design», who worked closely with contractor Semple Gooder Roofing Ltd., supervised by Peter McGoey and project manager Tom Shreeve, under general contractors Clifford Restoration Ltd. (project manager Fergus Tyrrell) who were co-ordinating the roof work with masonry restoration below. The result was the design and installation of a "Kit of Parts" comprised of 20 oz. copper roofing pans and 5,400 lineal feet of batten, with 6,100 knurled brass nuts holding in place 632 sections of 6 foot long skylight rafter caps. This approach allowed for many of the pieces to be fabricated with a great deal of precision off-site. Even considering the need for uniformity in the process, there were still special installation situations on-site, such as the gussets used at the base ot the battens on the east wing to protect vulnerable seams from wind driven rain. Once completed, the effect of such a large, uniform copper roof is quite impressive.

Over 42,000 pounds (19,000 kgs) of 20 oz. copper and lead-coated copper were used in this part of the restoration. (The copper roof Pumping Building at the south side of the site was completed in 2000.) The sheet materials were supplied by Canadian Brass & Copper of Concord, Ontario. A new Residue Management Facility is presently under construction at the R.C. Harris Treatment Plant immediately below the Filtration Building. By the time it is completed in 2007, the initial aging of the copper roof will be well advanced.