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This is a cross-section of the space between the dog and the house, which shows what happens during a heavy rainfall or snow melt (or, in the case of yesterday, both):
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After wasting some time trying to bail out the window well with a pitcher and a bucket, I decided to try my luck with a garden hose. Here's what I did:
1. Routed the hose from the patio to the low side of my lot.
2. Put a nozzle on the downhill end of the hose.
3. Attached the other end of the hose to a spigot near the window well.
4. Opened the spigot and nozzle. Once the air in the hose was pushed out, I closed the nozzle.
5. Closed the spigot, removed the hose and submerged its end in the flooded window well.
6. Opened the nozzle.
To my surprise, it totally worked! Controlling the flow of the water was a minor problem, though (if it's too fast, the window well temporarily dries up and the siphon loses its prime). It was too slow with the nozzle and too fast without it, so I partially restricted the flow by attaching the 'water in' tube from my wort chiller to the hose. Yet another reason to brew your own beer.