Backyard rink calculator

How to drain a backyard rink in spring

A liner rink does not drain itself. When the ice melts, the water sits on the liner until you move it. The sources I found agree on the order: let the ice melt, pump or siphon the water out, then pull the liner. The step they leave open is how much water that is and how long it takes, so the calculator below works that out for your rink.

Your drain time

How the numbers are made

Ice melts to a little less water than its own volume: 1 in of ice (917 kg per cubic meter) gives 0.917 in of water. Multiply by the rink area, convert cubic feet to US gallons (7.48 per cubic foot), then divide by the pump rate. Take a 40 × 20 ft rink with 4 in of ice. That is 3.7 in of water over 800 square feet, about 1,830 gallons. A 30 gallon per minute pump needs 61 minutes. A 10 gallon per minute pump needs about 3 hours, and a 60 gallon per minute pump about half an hour.

The estimate assumes the water is the melted ice only. Snowmelt or rain on top adds to it, and the rink bed is rarely flat, so the last inches pool at the low end and take longer than the average suggests.

Pump, siphon or cut the liner

The rink builder Iron Sleek has a post on tearing a rink down for spring. It recommends an electric or gas pump with a discharge hose and gives one reference point: a 30 GPM pump empties a 20 × 46 rink in 2–3 hours. It calls siphoning slow but effective, and says the low flow gives the ground a better chance to absorb the water. Family Handyman suggests the same two tools: as soon as the ice melts, drain the area with a simple siphon or a submersible pump.

• Pump. Fastest controlled option, and the hose lets you choose where the water goes. Hardware stores often rent them.
• Siphon. Slow, gentle on the lawn, no rental. Good for a small rink or a last few inches.
• Cutting the liner. Quickest, and the one to be careful with. Iron Sleek warns that an improper approach can cause a lot of unnecessary headaches, and that repeated flooding can damage grass roots.

Checking the 20 × 46 benchmark

Iron Sleek does not say how deep the water was. Working backwards: 30 gallons per minute for 2 hours is 3,600 gallons, and for 3 hours 5,400. Over 920 square feet that is about 6.3 to 9.4 in of water. That is my arithmetic, not the maker's figure. It suggests the benchmark describes a rink holding several inches, a bit more than the 4 in of ice used in the examples here.

Pump rate changes everything

Your rink at three example pump rates. Check the rated flow on your own pump. Long hoses and lifting water uphill usually cut it.

By rink size

4 in of ice and a 30 GPM pump.

Where the water goes

• Plan the route first. Iron Sleek points out that a pump lets you aim the discharge at a suitable spot, such as a sewer, which is also a way to keep it out of a neighbor's yard. Check local drainage rules.
• Mind the lawn. Standing water under the liner can wake the grass early, and a liner over active grass can suffocate it (Iron Sleek). Family Handyman: get the liner up early in spring and the grass is not damaged.
• Lift out the ice chunks. Iron Sleek notes some ice can remain on the liner after pumping. Clear it before you unclamp.
• Avoid punctures. A hole lets the water flood the grass roots and leaves dead spots, according to the same post.
• The liner itself. Cut it into manageable strips, as Iron Sleek suggests. Family Handyman says to dispose of it because you need a new one next year, so budget for that using the liner size guide.

Deciding when to take the rink down? The lawn guide counts days under cover and has a take-down checklist.