The town of Keila is located on limestones of Middle Cordovian age, in an area with a flat relief, about 30 m above sea level. The surface cover is very thin - 0-3m and mainly consists of loam-moraine. The surface cover is thicker in the Keila river valley and reaches 8-12,5 m (it also consists of loam-moraine). In the western part of the city there is an old stone quarry where limestone was quarried at the beginning of this century. The Paemurd is also a stratotype of the Keila deposit.
The city gets its main drinking and industrial water from six boreholes of the Cambrian-Ventian water horizon, the depths of which are 193-215m. The consumption reserves of the water horizon are 4700 m3/day, the actual consumption is approx. 3700 m3/day. Keila Terko, one of the largest grain storage and processing companies in Estonia, gets its necessary production water from two Ordovician-Cambrian groundwater horizon wells located in the southern part of the city, 90m and 72m deep. The water resources of the respective water horizon are 1000 m3/day, consumption is approx. 400-500 m3/day. Mudaugu residential area also receives water from the Ordovician-Cambrian water horizon (borehole depth 88m).
To the south of Keila are large peat deposits (Ohtu, Ääsmäe, Suure-Aru).
The administrative boundaries of the city include extensive forest areas, totaling approx. 340 ha. Mostly pines prevail, hazels are also common as an understory. The largest city parks are Keskpark, Jõepark and Männik
Bodies of water
The eastern part of the city is bordered by the Keila River, which flows into the Gulf of Finland in the Keila-Joa area. The sea is 11 km from Keila, the nearest lake is Kloogal, approx. 10 km away.
The river park, Liivaaugu dam and Loigu twisted juniper are under nature protection in Keila. Within the city limits, to the north of the Keila-Niitvälja railway, there are also a number of marshy areas where rare protected plants can be found (footworts, etc.).