Famous Drain Solution

Neighbor-Side PVC Manifold Plan

A precise, on-site guide to building a surface-mounted 4-inch Schedule 40 PVC trunk line. This system collects 4 downspouts from a shared concrete slab, protects the pipe from UV, and routes the water safely through the fence into a permaculture mulch trench.

Master Parts List

Core Plumbing

  • 4" Schedule 40 PVC Pipe Measure total length
  • Low-Profile Catch Basins 4x (Under downspouts)
  • 4" PVC Wye (Y) Fittings 3x (For tie-ins)
  • 4" PVC Cleanout & Plug 1x (At highest point)
  • PVC Primer & Cement 1x Combo Pack
  • 4" Pop-Up Emitter/Grate 1x (Fence exit)

Anchoring & Finish

  • Composite Shims 1x Pack (Never use wood)
  • 4" Galv. 2-Hole Straps 1 per 4ft of pipe
  • 3/16" x 1-1/4" Tapcons 1x Box (Blue screws)
  • 100% Ext. Acrylic Latex Paint 1x Gallon
  • 220-Grit Sandpaper 2x Sheets
  • Exterior Primer 1x Pint (For fence hole)

The Optician's Slope Trick

To guarantee a perfect 1/8-inch per foot slope without constant math, take a standard 2-foot carpenter's level. Tape a block of wood exactly 1/4-inch thick to one end. When you place this level on the pipe (with the block resting on the downhill side), adjusting the pipe until the bubble reads perfectly level means you have achieved precisely a 1/8" pitch per foot!

Phase 1: Preparation & Layout

  1. Dry Fit the Trunk: Lay the 10-foot sections of 4" PVC along the concrete where you want the line to run. Connect them loosely with the Wye (Y) fittings where the downspouts will tie in.
  2. Set the Slope: Using your modified 2-foot level, start at Downspout #1 (the highest point). Place composite shims under the pipe to achieve that perfect level bubble (1/8" drop per foot) across the entire run.
  3. Mark the Anchors: Once sloped perfectly on the shims, use a Sharpie to mark the concrete every 4 to 5 feet where you will place the galvanized pipe straps.

Phase 2: Anchoring to the Slab

You must secure the pipe so rushing water and thermal expansion don't shift your calibrated slope.

  1. Drill: Move the pipe aside slightly. Using a hammer drill and a 5/32" masonry bit, drill pilot holes into the concrete at your Sharpie marks.
  2. Secure: Place the pipe back onto its composite shims. Put the galvanized 2-hole pipe straps over the PVC, and drive the blue Tapcon screws into the concrete. Caution: Do not over-tighten and crack the plastic.

Phase 3: The Downspout Tie-ins

CRITICAL: Do not connect the aluminum downspouts directly to the PVC without a debris filter.

  1. Catch Basins: Place a low-profile catch basin on the concrete directly under each neighbor's downspout.
  2. Connect to Trunk: Run a short piece of 4" PVC from the basin to the Wye (Y) fitting on your anchored trunk line. The "Y" must point downstream toward the fence.
  3. Weld Joints: Once everything is perfectly positioned, use PVC primer (purple) and cement (clear) to permanently bond every single joint.

Phase 4 & 5: The Fence Pass-Through

  1. The Cut: Where the trunk line meets the fence, trace the circumference of the pipe. Use a 4.5" hole saw to cut a clean circle through the wood kickboard.
  2. Seal the Wood: Paint the inside of the cut hole with exterior primer to seal the raw fibers and prevent fence rot.
  3. The Exit: Slide the trunk line through the hole. It should protrude 2 to 4 inches into your yard.
  4. The Hand-Off: Attach a 4" PVC Pop-Up Emitter or an angled grate to the end of the pipe on your side. Ensure this dumps directly into the head of your 24-inch mulch trenches (bioswales).

Phase 6: UV Protection (Painting)

Standard white PVC degrades and becomes brittle under UV light. It must be protected to survive St. Louis summers.

  1. Scuff: Lightly sand the entire exposed PVC pipeline with 220-grit sandpaper to remove the glossy manufacturing sheen. Wipe away the dust.
  2. Paint: Tape off the concrete. Paint the pipe entirely with 100% exterior acrylic latex paint. Matching the color to the concrete or foundation will make the massive pipe visually disappear while giving it decades of UV armor.