Thirlmere Dam

Shasowing the Duke of Edinburgh Silver hike took us over the Thirlmere Dam. It is said to have raised the water 20 metres above the old stream level. I have read about the Thirlmere Aqueduct. It heads south for nearly 100 miles to Manchester with the water flowing only under gravity. It is never pumped. The dam is 190m above sea level. I'm not sure how high Manchester is above sea level, but the water is going down less than 2 metres every mile. It's going to be about 1 metre down every 1000 metres or 1mm every metre. Put like that, it doesn't sound much!