NDS Flo-Well dry well (flow well)

NDS Flo-Well dry well: what we stock

Flo-Well specs

Specs from the NDS product page and Flo-Well FAQ. NDS spells the product Flo-Well.

How does a Flo-Well dry well work?

Runoff from a downspout, catch basin or channel drain runs by pipe into the chamber. The chamber holds it while it seeps out through the weep holes and the stone around it. The inside is open, with no gravel, so NDS rates it at 250% more detention volume than a stone-filled dry well of the same size.

Units connect in series or stack to add storage. NDS has an online calculator that sizes the number of units from drainage area, surface type, backfill and native soil. NDS also advises an overflow, set lower than the lowest inlet, in case the system fills.

Install spec per NDS

• Wrap the unit in filter fabric and knock out all thirty 1" holes when fabric is used
• Backfill with 3/4" to 1" drain rock. Fabric around the rock also keeps soil out
• NDS example: a 4' dia. x 4' deep hole takes a little under 1.5 cubic yards of rock and holds about 165.5 gallons with the rock voids
• Use the bottom panel for light vehicle traffic or when stacking
• When stacking, run a 4" SDR 35 center support pipe from the bottom panel to the surface inlet
• Keep at least 8" of cover over the top

Bigger jobs: leaching chambers

When the storage needed runs past a few Flo-Wells, the job usually moves to chambers. We stock ARC leach field chambers (3613 and 3616 high capacity) and Cultec 150 and 330 HD Recharger starters and runs. Size them from the site plan.

Questions about NDS Flo-Well dry well

What does a flow well do?

A flow well, or dry well, collects stormwater from downspouts, catch basins or channel drains and lets it soak into the ground instead of pooling on the surface. The NDS Flo-Well holds about 50 gallons per unit in an open HDPE chamber. The stone around it adds storage.

How do you install a flow well?

Per NDS: dig the hole, wrap the unit in filter fabric, knock out the 1" weep holes, set it on drain rock and backfill around it with 3/4" to 1" rock. Keep at least 8" of cover over the top. Stacked units need the bottom panel and a 4" SDR 35 center support.

How many Flo-Wells do I need?

It depends on the drainage area, the surface type, the backfill and the soil under the unit. NDS publishes an online Flo-Well calculator for this. Units can be connected in series, 18" apart, or stacked up to 4 high to add storage.

Does the Flo-Well come with a bottom panel and fabric?

The complete Flo-Well kits Yankocy sells include the bottom panel. Filter fabric wrap is sold separately, and we also stock the 6" surface inlet with grate. NDS calls for wrapping the unit in fabric and using the bottom panel under light traffic or when stacking units.

Can you drive over a Flo-Well?

NDS rates it for light vehicle traffic, loads up to 175 psi, when buried with at least 8" of cover to the top of the unit. NDS calls for the bottom panel in that case. It can go as deep as 8'. At that depth the soil above sets the load it can take.

Last updated November 2, 2026

Yankocy sells NDS Flo-Well dry wells wholesale to lumber, mason and landscape yards. Buying for your own home? Your local lumber or mason yard can order it for you.

NDS Flo-Well dry well data sheets and sources

• NDS: Flo-Well Dry Well product page
• NDS: Flo-Well FAQ (PDF)
• NDS: Flo-Well assembly and installation manual (PDF)
• NDS: FWAS24WH 50 gal. Flo-Well kit

Related to NDS Flo-Well dry well

• NDS channel drains
• SDR-35 pipe
• Septic distribution boxes
• Silt fence
• All drainage & septic