▁the ▁same ▁purpose . ▁ ▁Typ ically , ▁the ▁air l ift ▁is ▁constructed ▁from ▁a ▁ 3 - met re ▁to ▁ 1 0 ▁met re ▁long , ▁ 1 0   cm ▁diameter ▁pipe . ▁A ▁cont roll able ▁com pressed ▁air ▁supply ▁v ents ▁into ▁the ▁inside , ▁lower ▁end ▁of ▁the ▁pipe ▁( The ▁input ▁end ▁always ▁being ▁the ▁lower ▁end ). ▁Com pressed ▁air ▁is ▁inject ed ▁into ▁the ▁pipe ▁in ▁one ▁to ▁three ▁second ▁burst s ▁with ▁an ▁interval ▁long ▁enough ▁to ▁let ▁the ▁resulting ▁b ubble ▁to ▁rise ▁to ▁the ▁higher , ▁output ▁end ▁of ▁the ▁pipe . ▁The ▁b ubble ▁moves ▁water ▁through ▁the ▁pipe ▁su ck ing ▁de br is ▁from ▁the ▁lower ▁end ▁and ▁depos iting ▁it ▁from ▁the ▁upper ▁end ▁of ▁the ▁pipe . ▁E ject ed ▁de br is ▁can ▁be ▁either ▁cast ▁off ▁( as ▁in ▁simply ▁removing ▁over bur den ) ▁or ▁collected ▁in ▁a ▁mesh ▁c age ▁for ▁ins pection ▁( as ▁more ▁often ▁is ▁the ▁case ▁in ▁na ut ical ▁arch ae ology ). ▁It ▁is ▁often ▁designed ▁to ▁be ▁hand - oper ated ▁by ▁a ▁diver . ▁ ▁Airl ift ▁p umps ▁are ▁used ▁by ▁water ▁util ities , ▁far mers ▁and ▁others ▁to ▁extract ▁water ▁from ▁deep ▁well s . ▁In ▁such ▁cases ▁the ▁pip es ▁can ▁be ▁ 3 0 , ▁ 6 0 ▁or ▁more ▁meters ▁deep ▁under ground . ▁Airl ift ▁p umps ▁are ▁govern ed ▁by ▁the ▁physics ▁of ▁two -