Grundfos · Submersible Pump End
16S SP 4 in Pump End
16 GPM class stainless steel SP pump end, motor not included: 9 builds for 1/2 to 10 HP motors, on 4 in and 6 in motors.
16 GPM Rated Flow
1/2-10 HP
112-1,636 ft Nominal Head
1-1/4 in NPT Discharge
4 in and 6 in Motor Fit
Grundfos Motor Flange
Built-In Check Valve
AISI 304 Stainless Steel
cCSAus
6.8-74.5 lb Weight
What Ships and What It Needs to Run
Included: the Grundfos 16S SP pump end with its built-in check valve; DS builds come built into a stainless steel sleeve.
Submersible motor required, ordered separately. The pump end mounts on a 4 in or 6 in submersible motor with a Grundfos motor flange, plus the motor’s control: a control box for a single-phase 3-wire motor, or a starter or drive for a three-phase motor. The motor horsepower and diameter for each build are in the Models & Ratings table.
Overview
The Grundfos 16S is the 16 GPM class of the SP 4 in submersible range, sold here as the pump end alone: stainless steel chambers and impellers with a built-in check valve, ready to mount on a submersible motor. Pump and impellers are AISI 304 stainless steel. Use it to rebuild an SP installation on a sound motor, or to build a pump around a motor you already have; the complete 16S pump with a Grundfos motor is listed separately.
The 16S pump end has a Grundfos motor flange and a splined or cylindrical shaft end, per build. Match the motor horsepower and diameter in the selector, and the flange to your motor; send us the motor model and we will confirm the fit.
Genuine Grundfos equipment, factory-new in original packaging — sold and supported by Watermain Supply, an independent industrial supplier.
Warranty
24 months from date of installation, but not more than 30 months from date of manufacture. In Grundfos's words, products are “warranted to the original user only to be free of defects in material and workmanship”; the full terms are in the installation and operating instructions on the Data Sheet tab.
Single Pump or a Set?
Each pump end builds one pump for one well. For a duty/standby pair, or a flow outside the 16S range, send us the duty: the other SP 4 in flow classes run from 5 to 77 GPM, and we will size the set with you.
Check the Part Number
The model code reads flow class, horsepower and stages: 16S20-18 is the 16S for a 2 HP motor with 18 stages. In the selector, choose the motor horsepower and diameter first, then the model; each model shows the head it adds at 16 GPM. Order by part number; every build is in the Models & Ratings table.
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16S75-56DS, 16S100-75DS: DS (deep set) builds, built into a stainless steel sleeve with an NPT male discharge.
- Some models come in a 4 in motor build and a 6 in motor build under different part numbers; the selector shows the motor size with the horsepower.
Models & Ratings
| Model |
Part No. |
Motor HP |
Motor |
Discharge |
Min. Well |
Nominal Head at 16 GPM, ft |
Net Weight, lb |
| 16S05-5 |
10010005 |
1/2 |
4 in |
1-1/4 in NPT female |
4 in |
112 |
6.8 |
| 16S07-8 |
10010008 |
3/4 |
4 in |
1-1/4 in NPT female |
4 in |
177 |
8.2 |
| 16S10-10 |
10010010 |
1 |
4 in |
1-1/4 in NPT female |
4 in |
223 |
9.3 |
| 16S15-14 |
10010014 |
1-1/2 |
4 in |
1-1/4 in NPT female |
4 in |
313 |
11.0 |
| 16S20-18 |
10010018 |
2 |
4 in |
1-1/4 in NPT female |
4 in |
397 |
12.8 |
| 16S30-24 |
10010024 |
3 |
4 in |
1-1/4 in NPT female |
4 in |
533 |
15.7 |
| 16S50-38 |
10110038 |
5 |
4 in |
1-1/4 in NPT female |
4 in |
832 |
30.2 |
| 16S75-56DS |
10310056 |
7-1/2 |
6 in |
1-1/4 in NPT male |
6 in |
1224 |
57.8 |
| 16S100-75DS |
10310075 |
10 |
6 in |
1-1/4 in NPT male |
6 in |
1636 |
74.5 |
Part numbers, horsepower, motor size and minimum well: Grundfos US price list, effective January 1, 2026. Nominal head: Grundfos SP data booklet, 60 Hz, May 2026 (complete-pump tables for the same model and motor size; where two figures are shown, builds on different motors or voltages differ slightly). Discharge thread and net weight of the pump end: Grundfos Product Center.
Shared Specifications
| Specification |
Value |
| Rated flow |
16 GPM |
| Motor horsepower |
1/2 to 10 HP |
| Motor |
4 in or 6 in submersible motor, Grundfos motor flange |
| Discharge |
1-1/4 in NPT; male on DS builds |
| Minimum well |
4 / 6 in (per build, Models & Ratings table) |
| Check valve |
Built in |
| Liquid temperature |
Up to 140°F (60°C) at the pump end; the motor sets the working limit |
| Approvals |
cCSAus and CULDWUS (Grundfos Product Center codes) |
| Curve tolerance |
ISO 9906 |
| Included |
Pump end only; motor and its control ordered separately |
Performance — Will It Do What You Need?
Every 16S is rated at 16 GPM. The nominal head in the Models & Ratings table is the total head Grundfos publishes for each model at that rated flow, in feet. Pick a model whose nominal head covers your pumping level plus the pressure you need at the surface (2.31 ft per psi) plus pipe friction.
Source: Grundfos SP data booklet, 60 Hz, May 2026 (SP 16S tables, pages 41-42). Performance conforms to ISO 9906. The 16S head curves are in the product images, and the 16S data sheet on the Data Sheet tab carries the full curves and tables.
Before You Buy — The Limits That Decide the Fit
| Check |
What to confirm |
| Motor |
A 4 in or 6 in submersible motor of the horsepower in the selector, with a Grundfos motor flange; ordered separately |
| Motor control |
Control box for a single-phase 3-wire motor; starter or drive for a three-phase motor |
| Well size |
Casing ID at least the minimum well for the build (Models & Ratings table) |
| Duty point |
Choose the model from the Grundfos curve at your flow and total head. Send us the pumping level, pipe run and pressure and we will check it against the curve |
Materials of Construction
| Part |
Material |
| Pump |
Stainless steel, EN 1.4301 (AISI 304) |
| Impellers |
Stainless steel, EN 1.4301 (AISI 304) |
Source: Grundfos Product Center.
