From splash causes to a recorded check
What makes a faucet and basin pair splash?
The makers quoted here point to a mismatch between spout height, reach and basin shape. hansgrohe’s consumer page says a flat sink with a high faucet, or a vanity in which water lands at the wrong angle, can lead to splashing.
Roca UK says a high tap with a shallow basin creates unwanted spray. hansgrohe also names the opposite fault: a faucet that is too low limits space at the sink. Neither page gives a dimension at which splashing starts.
| Term | What it means here |
|---|---|
| Spout height | How high the outlet sits above the basin. |
| Spout reach | How far the outlet projects over the basin. |
| Landing point | Where the stream meets the basin. |
| Free space | hansgrohe: room to move between spout and drain. |
| Water column | Dolphin Solutions: the stream from faucet spout to washbasin. |
| Stream type | Neoperl: aerated, laminar, spray or multi-stream. |
How do makers test a faucet and basin pair?
hansgrohe tests the assembled pair for free space, for splashing on opening and closing, and for splashing during hand washing. The steps follow its US trade page, which gives no pressures or pass limits.
- The faucet is assembled following its installation specifications.
- A test ball is placed between faucet and sink to check hand space.
- If the ball does not fit centrally under the jet, this test does not recommend the pair.
- The faucet is opened and closed several times; the sink is wiped dry in between.
- The spray test is repeated at different pipeline pressures.
- A standardized hand model swivels back and forth three times under the running jet; splashes outside the sink are evaluated.
Duravit says of its BestMatch test that every splash is counted, across four defined zones, and that washing comfort is measured with washing simulations. Its page gives no limits.
Where should the stream land in the basin?
No source used here names one correct landing point. Each row is that source’s own statement.
| Source | Its statement | Applies to |
|---|---|---|
| Dolphin Solutions, listing WELL requirements | Water not directly into the drain unless a domed waste trap is installed; new washbasins: water column at least 200 mm long and at least 75 mm from any edge | Handwashing washbasins, for WELL Certification; no version named |
| Kohler installation guide | Wall-mount faucet recommended, its spout at least 5 in (127 mm) long for proper performance; splashing is not mentioned | Sinks K-2191, K-2200, K-14222, K-14223, K-45922 |
| Dolphin Solutions, own advice | Faucet length just short of the trap rather than over it | Washbasin faucets |
| Geberit | A version extended by 40 mm; says extended projections prevent splashing | Its wall-mounted faucets for private bathrooms |
Dolphin Solutions gives one example. In a 350 mm washbasin, a 180 mm faucet sends the flow against the inside edge near the top of the basin, where it can ricochet out; a 150 mm faucet sends it to the basin base. That is one example, not a rule.
Which faucet height suits which basin type?
GROHE and Roca each sort basin faucets by height and say what each size suits. The size names are their own.
| Basin or use | Named size | What the maker says |
|---|---|---|
| Cloakroom | GROHE XS-Size | Extra small; usually cold water only. |
| Regular basin | GROHE S-Size | Standard height. |
| Vessel-style basin | GROHE XL-Size | Extra large. |
| Compact basin | Roca UK reduced height | Roca: best for compact basins. |
| On-countertop basin | Roca UK medium-plus or extended | Roca: needed for an on-countertop basin. |
The sources do not say that one maker’s size names match another’s, so compare dimensions, not names.
How do flow rate and stream type affect the check?
Flow rate, pressure and the outlet device are part of the setup being checked; hansgrohe repeats its spray test at different pipeline pressures.
WaterSense flow limit
The EPA’s bathroom faucet page says labeled bathroom sink faucets and accessories use at most 1.5 gallons per minute, against a standard flow of 2.2.
Scope and proposal
The label covers private lavatory faucets, such as those in homes and hotel guest rooms. A draft Version 2.0 proposes 1.2 gpm; the EPA page says that, as of February 2025, work on it is paused.
Stream type
Neoperl, an aerator maker, describes an aerated stream as water with air added and a laminar stream as turbulence-free and clear.
Stream angle
Neoperl says many of its models limit the flow rate, and that on aerators with its SSR function the stream angle can be adjusted.
- Flow rate, with its stated pressure
- Aerator type and code
- Stream angle setting, if adjustable
- Supply pressure during the check
Do faucet standards cover splashing in a basin?
The public scope pages of the two faucet standards used here describe the fitting, not basin splashing. The one splash condition found is a WELL requirement, as listed by a maker.
ASME A112.18.1/CSA B125.1
CSA Group’s store page for the 2024 edition gives the scope as plumbing supply fittings and accessories between the supply stop and the terminal fitting, including lavatory supply fittings.
EN 817
BSI’s page for BS EN 817:2024 says the document specifies leaktightness, pressure resistance, hydraulic performance, mechanical strength, endurance and acoustic characteristics of mechanical mixing valves, among others.
WELL, as listed by a maker
Dolphin Solutions lists as a WELL Certification requirement that water must not splash outside the washbasin when the faucet is opened in full.
WELL is a certification program, not a plumbing code. Neither the standards nor the WELL text was read; confirm any requirement with the local authority.
What does a maker’s pairing result cover?
A maker’s result covers the combinations that maker tested, set up its own way. A pair outside its lists has no published result.
| Program | What the maker says |
|---|---|
| hansgrohe ComfortZone Test | Its faucets with standard sinks from leading manufacturers; more than 12,000 combinations tested, by its count. |
| Duravit BestMatch | Tested for splashing and hand space; a best match must also fit visually and in price range. |
| GROHE BestMatch | All combinations tested at its test center in Hemer, Germany; the brochure names no test criteria. |
How should a buyer run and record a pairing check?
Mount the pair as it will be installed, make the observations below and record the setup with the result. This is a suggested record, not a published test standard; agree the procedure and acceptance with the project team first.
- Name the pair. Basin and faucet codes, spout variant, aerator.
- Fix the mounting. Position, spout height and reach.
- Set the supply. Record pressure and flow setting.
- Open and close. Note where water leaves the basin.
- Run steady flow. Note where the stream lands.
- Wash hands. Note hand space and splashes.
- Change one thing at a time. Basin variant, aerator or position.
Report what you saw, not a guarantee
State the result for the configuration checked: no splashing outside the basin was seen in the agreed sample check. That is narrower than saying the faucet never splashes. Re-check after any change to spout, aerator, basin or flow setting.
What should you send and ask before a quotation?
Send the pair and its mounting, and ask what evidence exists for that exact pair.
| Question | Why it matters |
|---|---|
| Has this exact pair been checked with water running? | A result covers the combination tested. |
| How was the faucet mounted? | Height and reach change where water lands. |
| At which pressure and flow setting? | A new setting is a new observation. |
| Which aerator is fitted? | The outlet device shapes the stream. |
| Is there a record with model codes? | Without the setup, it cannot be compared. |
Include with your request
- Basin and faucet drawings and codes
- Mounting: deck, wall or countertop
- Supply pressure range on site
- Flow limit or label required
- Any pairing result you already hold
If no pairing check was done, say so on the order. WNS Global confirms any offered faucet, basin and commercial terms separately in writing. This guide does not state that any WNS Global faucet, basin or pair has been splash-tested or meets any flow limit, standard or rating named above.
