kˈeɪsɪŋ tə səpˈoːɹt ðɪ ɛkstˈɜːnəl sˈɜːfɪsᵻz ʌvðə bˈoːɹhoʊl ɐɡˈɛnst kəlˈæps mˈeɪ biː nˈiːdᵻd, ˈiːðɚ tˌɛmpɚɹˈɛɹᵻli ɔːɹ pˈɜːmənəntli, ænd ɪz ˈɔfən mˌeɪd ʌv pˌiːvˌiːsˈiː pˈaɪp, wˌɪtʃ hɐz ðɪ ɐdvˈæntɪdʒᵻz ʌv bˌiːɪŋ bˈoʊθ tʃˈiːp ænd ɪnˈɜːt.
Casing to support the external surfaces of the borehole against collapse may be needed, either temporarily or permanently, and is often made of PVC pipe, which has the advantages of being both cheap and inert.