FAQ
TL;DR: Typical mains pressure is 3 bar [WRAS, 2021]. "Use a tee under the sink" [Elektroda, Kenworth 18, #17300225]. Connect via a 1/2 inch tee plus 3/4 inch valve, or a proper faucet diverter—not a garden-hose adapter [Elektroda, teskot, post #17300270]
Why it matters: This FAQ helps renters/DIYers cleanly connect a dishwasher to a tap or under-sink line without losing sink use or risking leaks.
Quick Facts
- Dishwasher inlet connection: Typical G3/4 (3/4" BSP) female on the hose; mate to a 3/4" male valve [Bosch, 2023].
- Common European faucet aerator threads: M24x1 (male spout) and M22x1 (female spout) (“NEOPERL Aerator Thread Sizes”).
- Supply pressure: Typical 3 bar; many dishwashers operate approx. 0.5–10 bar [WRAS, 2021]; [Bosch, 2023].
- Backflow: EN 1717 requires protection; use a check valve or a washing-machine angle valve with non-return (“EN 1717 Backflow Prevention”).
- Portable/countertop units often include a faucet diverter; water use approx. 7 L/cycle [Danby, 2022].
Can I connect a dishwasher directly to my kitchen tap?
Yes, if you use a faucet diverter that threads onto your aerator (M24x1 or M22x1) and provides a G3/4 outlet for the inlet hose. Avoid simple garden-hose adapters; they are “completely unsuitable” for dishwashers [Elektroda, teskot, post #17300270] Many countertop models include a diverter in the box [Danby, 2022]. Typical tap threads are M24x1/M22x1 (“NEOPERL Aerator Thread Sizes”).
What’s better: under-sink tee or tap adapter?
Under-sink tee keeps the faucet usable while the dishwasher runs. “Then, while the dishwasher is running, the batteries can be used simultaneously.” [Elektroda, Kenworth 18, #17300225]. A faucet adapter can work but may block normal use unless it’s a diverter [Danby, 2022]. Typical mains pressure is 3 bar, adequate for both branches if fittings are sized correctly [WRAS, 2021].
How do I tee into the cold feed under the sink (3-step)?
- Shut off water. Insert a G1/2 tee between the cold angle stop and the faucet hose [Elektroda, Kenworth 18, #17300225].
- On the tee’s spare port, fit a washing-machine angle valve 1/2" x 3/4" (G1/2 to G3/4) (“Schell 1/2 x 3/4 washing machine valve – Castorama”).
- Connect the dishwasher’s G3/4 hose; open water and check for leaks (“Castorama 1/2" Tee Fitting”).
What exact adapters do I need to go from faucet spout to a dishwasher hose?
Identify your aerator thread. For a male M24x1 spout, use M24x1 female to G1/2 female, then a G1/2 male to G3/4 male nipple, then attach the hose [Elektroda, Kenworth 18, #17300294]. Aerator threads are fine and can be tricky to match [Elektroda, Kenworth 18, #17300250]. Common spout threads: M24x1 and M22x1 (“NEOPERL Aerator Thread Sizes”).
Is a garden-hose adapter okay for dishwashers?
No. The forum expert called the shown garden-hose adapter “completely unsuitable” due to mismatch and lack of proper control/diversion [Elektroda, teskot, post #17300270] Use a purpose-built faucet diverter that switches flow between the spout and appliance [Danby, 2022]. Typical faucet aerators flow 6–9 L/min at 3 bar, which diverters are designed to manage (“NEOPERL Flow Rate Guide”); garden fittings aren’t.
Will my faucet still work if I connect at the spout?
Only if you install a faucet diverter with a bypass. Without a diverter, the tap becomes unavailable while the dishwasher runs [Elektroda, Koslo, post #17311496] Countertop kits include quick-connect diverters that toggle between tap and appliance [Danby, 2022]. Expert tip: “Use a tee under the sink” to keep full tap function [Elektroda, Kenworth 18, #17300225].
Stores told me it can’t be done. Any workaround?
Specialist water/sewage suppliers and online shops stock the required reductions and diverters [Elektroda, Kenworth 18, #17302121]. One user combined “several gardening parts” to make it work, with the tap inactive only during dishwasher use [Elektroda, Koslo, post #17311496] Aerator reductions can be rare in big-box plumbing aisles—check dedicated plumbing or hydronic suppliers [Elektroda, Kenworth 18, #17300250].
Which thread sizes and standards matter here?
Dishwasher inlets are typically G3/4 (3/4" BSP) female on the hose; they connect to a G3/4 male valve [Bosch, 2023]. Faucet supplies under-sink are commonly G1/2 (1/2" BSP) (“Castorama 1/2" Tee Fitting”). Faucet spouts use metric aerator threads, often M24x1 or M22x1 (“NEOPERL Aerator Thread Sizes”).
Do I need a check valve or backflow protection?
Yes. EN 1717 requires backflow protection to safeguard drinking water. Use an angle valve with an integrated non-return (or add a separate check valve) on the dishwasher branch (“EN 1717 Backflow Prevention”). Many washing-machine/dishwasher valves include this feature by design (“Schell 1/2 x 3/4 washing machine valve – Castorama”).
Should I connect to hot or cold water?
Follow the manual. Many dishwashers prefer cold, with optional hot up to approx. 60°C if allowed [Bosch, 2023]. Supplying too-hot water can impair detergents and increase scale. Typical mains pressure is 3 bar; stay within the appliance’s rated range [WRAS, 2021]; [Bosch, 2023].
How much flow do I need, and do diverters restrict it?
Dishwasher fill is intermittent and modest. Countertop units use about 7 L per cycle [Danby, 2022]. Typical faucet aerators deliver 6–9 L/min at 3 bar, which is ample (“NEOPERL Flow Rate Guide”); quality diverters maintain similar flow paths. Quote: “Use a tee… and buy a valve” for robust supply [Elektroda, Kenworth 18, #17300225].
Any edge cases where a tap connection fails?
Pull-out spray taps and proprietary aerators often don’t accept rigid diverters (“Danco Faucet Diverter Valve Specs”). Fine-thread aerators may lack matching reductions locally [Elektroda, Kenworth 18, #17300250]. Using garden adapters can leak or detach under pressure [Elektroda, teskot, post #17300270] In such cases, use the under-sink tee method [Elektroda, Kenworth 18, #17300225].
What tools and sealants should I use?
Use two adjustable wrenches, a bucket, and new flat washers where applicable. BSPP (G) threads seal with gaskets; use PTFE tape only on appropriate male threads, not on aerator gasketed joints (“ISO 228-1 (BSPP) thread sealing”). The under-sink tee plus angle valve approach is straightforward for DIYers [Elektroda, Kenworth 18, #17300225].
Will this affect warranty or safety?
Manufacturers expect a fixed, accessible shutoff on a cold line; deviating from instructions can affect warranty [Bosch, 2023]. Always include backflow protection per EN 1717, and check for leaks after each change (“EN 1717 Backflow Prevention”). If in doubt, choose the under-sink tee method recommended by forum experts [Elektroda, Kenworth 18, #17300225].
