. ▁ ▁Av ailable ▁water ▁supply ▁The ▁water ▁available ▁is ▁often ▁determined ▁by ▁means ▁of ▁a ▁water ▁flow ▁test ▁( open ing ▁a ▁fire ▁hyd rant ▁and ▁recording ▁the ▁water ▁press ures ▁and ▁gall ons ▁flow ▁per ▁minute ). ▁Some ▁municipal ▁water ▁juris dict ions ▁may ▁provide ▁their ▁own ▁estimate ▁of ▁available ▁water ▁supplies . ▁ ▁In ▁locations ▁where ▁a ▁municipal ▁connection ▁is ▁not ▁possible ▁or ▁practical , ▁the ▁needed ▁pip ing ▁network ▁may ▁draw ▁water ▁from ▁an ▁open ▁( la ke , ▁p ond , ▁river ) ▁or ▁closed ▁( under ground , ▁above ground , ▁elev ated ▁tank ) ▁water ▁source . ▁ ▁Where ▁the ▁water ▁supply ▁is ▁drawn ▁from ▁a ▁static ▁supply ▁like ▁an ▁under ground ▁tank ▁or ▁a ▁p ond , ▁hyd ra ul ic ▁calculations ▁will ▁also ▁determine ▁what ▁pressure ▁must ▁be ▁added ▁to ▁deliver ▁the ▁water . ▁This ▁pressure ▁is ▁typically ▁applied ▁by ▁means ▁of ▁a ▁fire ▁p ump ▁or ▁press ur ized ▁water ▁storage ▁tank . ▁ ▁System ▁pip ing ▁network ▁ ▁Supp ression ▁system ▁pip ing ▁networks ▁are ▁usually ▁arranged ▁in ▁one ▁of ▁ 3 ▁configurations : ▁Tree , ▁Loop , ▁or ▁Grid . ▁Tree ▁systems ▁may ▁be ▁imag ined ▁as ▁a ▁network ▁of ▁pip ing ▁starting ▁with ▁a ▁larger ▁tr unk ▁and ▁branch ing ▁out ▁to ▁progress ively ▁smaller ▁pip es ▁with ▁fire ▁spr ink lers ▁or ▁other ▁devices . ▁Loop ed ▁systems ▁may ▁have ▁a ▁larger ▁pipe ▁that ▁runs ▁throughout ▁a ▁building ▁and ▁t ies ▁back ▁to ▁itself ▁near ▁the ▁start , ▁with