The River Dodder rises at Kippure and flows through the valley, reaching the sea at Dublin Bay.

[1] The Glenasmole Valley is an EU-designated Special Area of Conservation.

The reservoirs, constructed between 1883 and 1887, supply 18.2 million litres of water per day.

There are no nucleated villages in the valley as most dwellings are one-off houses.

The small area encompassing the valley covers 30 square kilometres (7,413 acres), giving it a population density of 14.9 people per square km, making it the most sparsely populated region in County Dublin.