understood that the invention is not limited in its application to the details of the particular arrangement shown since the invention is capable of other embodiments also the terminology used herein is for the purpose of description and not of limitation fig1 a shows a side view of a novel l form 1 used in constructing an inground water containment holder such as a spa pool and manmade pond fig1 b shows a top view of the l form 1 of fig1 a along arrow a 1 fig1 c shows a bottom view of the l form 1 of fig1 a along arrow a 2 referring to fig1 a 1c the l shaped form 1 can include a vertical leg 10 having a substantially vertical planar back surface 12 having a height of approximately 17 inches a flat horizontal top end 14 of approximately 3 inches and a downwardly forward sloping front surface 16 form 1 can include a horizontal leg 20 having an inclined rear back surface 22 having an incline of approximately 45 degrees being approximately 16 75 inches long a flat planar horizontal longitudinal top surface 24 being approximately 16 5 inches long and a vertical planar front surface 26 approximately 12 inches in height with a lower flat planar tip end 28 approximately 8 inches in length l.