Geology
The town of Keila lies on limestone from the Ordovician Middle ages, on an area with flat terrain approximately 30m above sea level. The surface coating is very thin, 0-3m, and predominantly consists of sand and clay moraine. The surface is thicker in the valley of the Keila river, where it measures up to 8-12.5m and also consists of sand and clay moraine. There is an old limestone quarry in the western part of the town, where limestone was mined until the beginning of last century. The limestone quarry is also part of the stratotype of the Keila deposit.
The town gets its principal drinking and industrial water from six Cambrian-Vendian groundwater bore wells, which are 193-215m deep. The supplies of groundwater available for consumption are 4700 m3/day, while actual consumption is about 3700 m3/day. Keila Terko, one of the largest companies dealing with grain storage and processing in Estonia gets the water it needs for its production from two 90m and 72m Ordovician-Cambrian groundwater bore wells in the southern part of the town. The supplies of this groundwater are 1000 m3/day, while the consumption is about 400-500 m3/day. The Mudaaugu residential area also gets its water from the Ordovician-Cambrian groundwater reservoir from an 88-metre bore well.
Extensive peat deposits (Ohtu, Ääsmäe, Suure-Aru) can be found south of Keila.
Forests and green areas
The administrative borders of the town incorporate extensive forests totalling about 340 ha. These are predominantly pine forests, but there are also some hazel trees. The largest of the town parks are Keskpark, Jõepark and Männik.
Waterbodies
The eastern border of the town is the Keila river, which flows into the Gulf of Finland in the Keila-Joa region. The sea is 11 km from Keila, while the closest lake is in Klooga, about 10 km away.
Nature conservation
Jõepark, the Liivaaugu oak and the Loigu twisted juniper have been listed for nature conservation in Keila, and there are several swampy areas where rare protected plants such as orchis can be found within the borders of the town, north of the railway between Keila and Niitvälja.