Aerial Photo 
Existing Reservoir and Pump House

the city studies the possibility to pump water into a reservoir located on the mountain.

the city hires an engineer, Mr. Thomas C. Keefer, to produce a report

construction of the mctavish reservoir:
- oval shape
- uses natural rock to hold the water
  whenever possible
- low side held by masonry
- 24’ deep
- capacity 13,5 million gallons
- masonry wall divides the reservoir
- small gate house is built to store
  excess water


reservoir is enlarged to 16 million gallons



first steam pump
reservoir has a capacity of 37 million gallons

construction of the present pump house, containing 6 pumps
- addition to the pump house allows for a greater pumping capacity, with 6 more pumps.
- major restoration work is done on the reservoir, subdividing it into 6 tanks to facilitate maintenance and covering it.

1957 the reservoir has been covered and the old pump house as well as the new one coexist.
no major changes have been made to the reservoir since 1950. the pump house is now fully automated and the original pumping station has been demolished.



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Originally the McTavish reservoir was supplied by a gatehouse, which had a water driven pump. the first pump house was constructed in 1875 and was located on the southwestern tip of the site. It was designed in the French Renaissance style and would house the first steam pump to serve the reservoir. It’s original capacity was one half million gallons per day. By 1913 a centrifugal pump with a capacity of 12 million gallons per day was in place.

The pump house, in it’s present location, was constructed between 1928 and 1932.  Designed by the engineer Charles J. Desbaillets, it drew its inspiration from medieval castles from his native Switzerland.  The structure was made of steel and was clad with cut stone. The treatment of the windows is irregular and asymmetric. The whole composition was meant to be romantic and picturesque, with the chateau-style pump house casting its reflection into the reservoir, which was encircled by a wrought-iron fence.

The original pump room contained 6 pumps, 3 with a capacity of 12 million gallons per day and 3 with a capacity of 15 million gallons per day. In 1947 an auxiliary pump house was added to the building, also designed by Desbaillets. It was in the same style, however, it lacked the characteristic corbelled brackets of the original structure. The addition would house 6 more pumps, bringing the station’s capacity to 157.5 million gallons per day. 

The overall dimensions of the building are 365 feet in length and 60 feet in depth. Its height is 115 feet, to the top of the central tower, which is at 85 feet above Doctor Penfield Avenue. Today the pump house is fully automated and is controlled remotely from the Atwater filtration plant. The offices in the main tower are now abandoned. The reservoir itself is now outpaced by most of the newer reservoirs, in terms of capacity.
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In considering the structural system for any new buildings on the site, one must understand the existing condition of the reservoir itself. According to the available information, the first step in the covering  of the reservoir was the pouring of a 7” thick slab on the existing bedrock. The original wall, bisecting the reservoir was removed.  The reservoir was then divided into six cells, made of 2-foot thick walls, 25 feet 9 inches in height. The water level, in the tanks, is 24 feet. Each tank is separated from the next by a 28-inch space and water can travel between the tanks through 6X10- foot openings. The roof slab is 217 000 sq. ft in area and is supported by 456 columns, 22 inches in diametre, spaced 20 feet apart.
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The treatment steps of water filtration required to enhance the quality of the water are:

1. Rough screening: rough screening of raw water to intercept material or objects which might damage the low lift pumps.

2. Filtration: filtration on a siliceous sand-supported bacterial bed, which eliminates some floating matter and bacteria.

3. Ozonization: this process, which added to the water tretment at the Charles-J. Des Baillets plant, involves the injection of ozone into the filtered wate.  This substance is an oxidizing agent and a powerful disinfectant.

4. Chlorination: chlorination to ensure the water’s disinfection and maintain its quality until it reaches the consumer.  To achieve this, the amount of chlorine is modulated according to a predetermined value of the residual chorine.

Pumping and distribution of treated water:

Following disinfection, the water is fed from the Atwater and Charles-J Des Baillets plants via the pumping stations to the different distribution zones.

The territory is divided into six zones and a sub-zone created to accommodate the different elevations.



Strategy 1 - use of the existing column grid to develop a 20 foot by 20 foot module for the buildings. They would sit on this grid, but not on the walls of the tanks, avoiding the need to drain multiple tanks for the construction of one building.
Strategy 2 - use of the tank walls in addition to the column grid. This may necessitate draining multiple tanks at once during construction. The walls could, however, be excellent anchorage points for the new buildings and would dictate their overall shape.
Strategy 3 - placement of the buildings at the periphery of the reservoir and at the southwest corner of the site. Buildings constructed at the periphery would need to incorporate the service tunnel in any underground floors and could cantilever over the reservoir. The southwest corner of the site has a dominant position as well as being the site of the original pump house. There is also a steep slope, which could serve as a design cue for the building.
Structure 1 - structures keyed into the column gird are relatively low, 2-3 storeys
Structure 2 - when structures do not rest only on the tank, building height may be increased.

According to one source, only 3 inches of earth were placed to cover the roof of the reservoir. However, examinations on site have placed this figure in doubt.
One possible strategy is to “key-in” to the existing column grid. However, it must be determined if the columns need to be reinforced and if the walls of the tank can also be used as load-bearing elements. The existing column diametre and spacing, would suggest that it may be feasible to erect structures above the reservoir. Another strategy would be to place buildings along the periphery of the reservoir.


Geothermal system: is a heating and cooling system which provides high level of comfort.  It only requires relatively small amount of electricity which can concentrate what nature provides and than release high-quality heating or cooling inside a building.  They work on a different principle than an ordinary furnace/air conditioning system. 

To create heat, the earth’s natural heat is tapped by employing a series of below-ground pipes, called a loop, installed in the soil or submersed in a pond or lake.  A fluid circulating in the loop absorbs the earth’s heat in winter and carries it to the building where.  Indoor geothermal system then concentrates the heat and releases it at a higher temperature inside the building.  While in summer, the process is reversed, as excess heat is drawn from the building, expelled to the loop, and absorbed by the earth or water.

Geothermal system consumes less energy because the temperature of the groundwater beneath the earth’s surface remains relatively constant throughout the year, even though the outdoor air temperature may fluctuate greatly with the change of seasons.


Pond or Lake Closed Loop:   If the building or buildings are near a pond or lake, submersing the loop beneath the surface of the water is often the most cost-effective design.  This type of loop configuration requires minimum piping and excavation, but the pond or lake must be deep enough and have sufficient surface area.  The pipe may be coiled in a "slinky" shape to fit more of it into a given amount of space.  Fluid is pumped through the pipe, just as it is in a closed-loop ground system. GeoExchange experts recommend using a pond loop only if the water level never drops below six to eight feet at its lowest level to assure sufficient heat-transfer capability.  Pond loops used in a closed system result in no adverse impacts on the aquatic system.


Asselin, Manon, Imaging the unseen, History and Theory Thesis, McGill University.

Héritage Montreal, Les stations de pompage de l’aqueduc.

Héritage Montreal, Montreal Waterworks, Government publication, Service des travaux publics.

Lacoursière, Jacques, Chronologie de l’histoire de Montreal, Montreal, 1992, 129p.

Maffini, Guilio, The McTavish pumphouse, Student Paper, McGill University, School of architecture, 1970

Manning, G. P., Reservoir and tanks, London, Butler and Tanner Ltd., 1967, 384p.


Bibliothèque Nationale du Québec:
Album de rues E.-Z. Massicotte :

Cartes et Plans

City of Montreal:

. school of architecture . mcgill university .