Creative plumbers make a splash with Singin’ in the Rain water delivery and recovery system

By Wil Elliot

It isn’t every theatrical performance that comes with an audience advisory: “Audience members seated in the front rows may feel a few drops of water” and “there is the possibility of a splattering of water during the onstage scenes that feature rain.”

Ushers will have rain ponchos for those who wish to use them.” That said, it isn’t surprising considering every performance of Singin’ in the Rain uses over 14,000 L of water (the equivalent of 14 tonnes). The water used is recovered, cleaned and used again. Wil Elliot of Water Sculptures tells us how this was achieved at the recent Mirvish Singin’ in the Rain shows at the Princess of Wales Theatre in Toronto, ON.

The Singin’ in the Rain system was designed in 2013 and 2014 while Singin’ in the Rain was touring the UK, Japan, and then Australia, Singapore, South Africa, and other international venues for 16 months. The idea was to create rain for the stage but also to create a floor-level controlled flood on the set to allow the lead character and cast in the reprise at the end of act 2 to flick water around the set and into the audience.

The rain was designed as a heavy downpour of rain produced in a film setting as is the nature of the show. The flooding was created to add body to the rain and provide additional water to allow the performers to splash while dancing.

Considerations when creating the rain:

• Rain water volume for the main performance and reprise
• Water pressure at each rain nozzle
• Pump types
• How the rain would look on set
• Performer comfort temperature
• Recovery of the rainwater after each performance
• System failure prevention
• Water quality

Considerations when creating the flood:

• How do we contain the water
• The flow rate of water being delivered onto the set
• Time taken to fill the area on set
• Recovery of water from the set
• Water quality

Let it rain

Three rain bars on stage are set at eight metres above the set. Water is supplied to the rain bars using three 1.5 Kw submersible pumps. Each pump has the capacity to deliver 250 L of water/min at 11 m static head. Each pump has a regulating valve in-line for flow adjustment. To prevent a total system failure the show was fitted with three individual rain circuits so in the event of a pump failure the main effect was not lost.

To create the effect onstage stainless steel tubes were fabricated with welded outlets at 500 mm (19.5 in.) centres. A rotary valve is fitted to each outlet and each valve is fitted a full flood rain nozzle (this is the type of nozzle commonly used for cleaning processes). Each rain nozzle produces a full heavy rain effect with a maximum of 2.6 m diameter spray per nozzle. To achieve the maximum output each nozzle requires a pressure of 1.6 bar.

The system is a single end feed to each rain bar. Due to the low pressures involved it was determined this was the best operating system without the need for additional regulation at the individual rain nozzles. For the first sequence of a 4.5-minute routine the quantity of water used is 850 L with a further 500 L for the second sequence/reprise at the end of the show. Water is extracted from the two main water reservoirs in the stage wing to ensure sufficient water is available for each rain sequence. These reservoirs hold 7,500 L of water combined.

To maintain pressure within the system for the rain non-return valves were introduced at the outlet of each pump to hold both the water and pressure in the pipework. Each rain bar is also supported with an in-line isolating valve, which is operated for the rain sequence.

As with all live shows there is an element of debris from the performers and their costumes, which could potentially enter into the rain circuits and block a rain nozzle. Inline filter strainers at 40 Microns were installed between each pump and the delivery hose to remove potential debris from the line. These filters are removable for cleaning without pressure loss in the system when idle.

For performer comfort a 9.0Kw 400v water heater and circulating pump is installed into the 1,000 L containers. The water is heated to 37º C.

Equipment:

Rain water storage: 1,000 L containers

Effects Pumps: Submersible 1.5Kw 220v 60Hz

Wet connections: Dixon CamLok type

Effects bars: 7 no. 2.5 m stainless steel 1.5 in. diameter with ½ in. outlets @ 500 mm centres

Hose: 1.5 in. smoothbore rubber hose rated @ 10 bar

Heater: 9.0 Kw 400v 50/60Hz three phase heater

Heater pump: Submersible 0.5Kw 220v 60Hz

Flooding the stage (on purpose)

This was called the wet area for good reason. Two large 4,000-L water tanks provide all the water for the flooding sequence. These are linked with four-in. rigid PVC pipework allowing for combined flow of water for the flooding sequence and a balanced system for water treatment.

Flooding of the stage is a relatively straightforward process delivered by a single self priming end suction pump. The water is extracted from the large tanks via a two-in. outlet connected to the four-in. link. This permits a balanced stable suction from both tanks onto the performance area on stage. The flood water is delivered onto the stage with a two-in. rubber hose hidden under the deck of the set and connected to a CamLok connecter at the side of the stage pool. To prevent the risk of syphon, manual ball valves are fitted and opened just before the flooding sequence begins.

For splash reduction and noise suppression at the point of entry into the performance area a two-in. 45º elbow was fitted onto the CamLok connection inside the performance or wet area. A cone arrangement made from cord woven material was fitted around the elbow, which allowed the flow rate to be achieved with reduced noise and splash. To achieve sufficient flood depth of water on stage, precise adjustments to the flow rate into the pool were made and timings taken during the rehearsals prior to the opening performance. Once these were set, no further adjustment was needed.

Water recovery

At the end of the rain and flood sequence the direction of waterflow onto the stage was reversed using a second self priming end suction pump. Due to the levels of water on stage being no greater than 150 mm, the preferred recovery pump was the same type used for the flooding. This pump was located next to the flood pump off stage in the wing next to the main water tanks.

The pump was linked with a two-in. suction hose from the wet area back to the 7,500 L holding tank. A high-flow strainer filter was fitted at the end of the return line to remove performer debris prior to being returned into the tanks.

A two-in. 90º elbow was fitted with a castellated inlet to ensure an efficient evacuation from the wet area to the end of the suction pipe. This provided a low suction device in the wet area to remove 90 per cent of the water and send it back to the holding tanks.

The combined flood and suction pumps were located in a road case with all isolation and flow regulating valves on board for adjustment. This unit became affectionately known as the “Push me, pull you” unit on the set. It takes 15 minutes to drain all the water after each performance.

Equipment:

Water storage: 2 x 4,000 litres capacity polyethylene tanks

Effects Pumps: 2 x self priming end suction pumps. 2.2Kw 220v 60Hz

Hose: 2.0 in. smoothbore rubber suction and delivery hose rated @ 10 bar

Wet Connections: Dixon CamLok type

The wet area water containment

A custom fabricated liner was manufactured from the AutoCAD drawings for the set. The liner was constructed from 900 gm/m2 black tarpaulin and bespoke made to fit the socket of the water area. This type of material has a low degradation rate and a high strength rate, proven with over 300 performances to date without failure.

Electrical

All electrical equipment is distributed out from a 63 amp, three phase splitter with cables running out to the manual switch control panels. Everything is located on the right side of the stage close to the large tanks. All equipment is residual current device (RCD) protected individually.

Water quality

To maintain good water quality, a 150 sq. ft. cartridge filter with a 200-watt Ultraviolet C disinfection unit with a self priming end suction pool pump is utilized. A satisfactory flow rate is achieved between the two tanks and through the four in. connecting link. This provided a turnover rate of 6,000 L of water in 1.5 hours. The filtration plant removed suspended debris and lint from the water that got past the return filter from the suction pump. The circulated water is pH balanced and bromine treated to maintain a swimming pool quality.