DIY Water Tank from Profile Sheet for garden irrigation.

Hello.
Have made 2 water containers from profile sheet.
They're used to collect roof water and irrigate my garden.
Here, I describe step by step creation process.
A list of neccessary inventory is at the end. m3
Frame
• Bought the cheapest, thinnest profile sheet and smallest fasteners I could find in the city.
• Cut the sheet into 6 pieces of 1m each. For the 1st container, laid out 3 sheets overlapping along the wave.
• After marking, drilled 20 holes through the overlap and fastened them.
Did the same with remaining 2 overlaps.
Attaching to Pallet
• Had two leftover IBC metal pallets with factory holes.
• Since sheet was very thin, I used metal plates (stamped from scrap) to tie the frame to pallet.
• Cut out a circle of polystyrene foam by frame's diameter and laid it on the bottom. Thus, water pressure won't push the film out through the cracks between frame and pallet.
Film Installation
• Sealed frame edges with electrical tape to keep film from being torn.
• Checked if film easily wrapped outside the frame, so water tension won't reap it inside the frame.
• Cut a 2m long piece of film, considering the frame height (1m), future weld seam (5cm) and the bends at the edges.
• Placing paper in between, welded one end of the film. Held the iron in one place from 5 seconds and more, until seam becomes rough and stiff.
• Made a hole on film by cutting off the seam's corner tip. Mounted that corner on a pipe and inserted both into the hose. Secured that with a clamp.
• Placing bricks under my feet to reach the bottom, brought the hose out from below and straightened the film inside.
• With pins stamped from wire, pinned the film bends to the frame edges.
Notes
• Initially attached 3 metal strips to the sides of the 1-st container for rigidity. Turns out it wasn't necessary.
• Repeating the process, made another container, which has a little slant due to the different holes on 2-nd pallet.
• Connected outlet hoses with a tee. Installed a tap later.
• Brought some pieces of concrete slabs from a landfill and placed containers on them for higher water pressure.
• Filled containers with water and covered top with fiberboard sheets to keep the sun off the water. Now they're used to collect roof water and irrigate my garden.
Inventory
Tools:
• tape measure and marker
• metal scissors,
• screwdriver
• iron
Materials:
• profiled sheet - 1sheet/6m,
• polyethylene film - L: 4m, W: 1.5m
• 3/6mm bolt, nut, two washers - 60/60/120 per container
• pallets - 2 pcs.
• polystyrene foam: 1m2/30mm
• knitting wire
• electrical tape
• pipe, hose, clamps
• tee and ball valve