If flow stopped immediately after a hand-shower hose change, check the exact hose arrangement before blaming house pressure. Waterpik's cited instructions show a directional vacuum-breaker end on covered hoses and warn that incorrect installation prevents flow. Confirm its label, compatible connections and the specified washers with water off. Preserve the protective device; do not remove it to restore spray.
Use the timing of the change
If the hand shower worked before a hose replacement and stopped immediately afterward, start with the installed parts and their directions. That history is useful; it does not prove the house pressure, wall valve or hose is otherwise healthy.
This answer uses Waterpik's actual shower FAQ and standard hand-shower manual. Identify the complete shower model and hose part before changing connections. A similar thread or appearance does not establish that a replacement is compatible.
Check the marked protective end
Waterpik's FAQ says some hoses contain a vacuum breaker, a device that prevents water flowing back toward the supply. On the covered arrangement, its end belongs closest to the supply; incorrect hose direction can prevent water flow.
The standard owner manual, FN 20022557-F AC, identifies a sticker reading “attach this vacuum breaker end to shower bracket.” Compare the installed ends with that label and the actual diagram. Other hose designs can have different identification, so do not choose direction from a ridged or smooth nut alone.
Preserve the required protective device. Do not remove its internal parts, force it open or replace a directional hose with an unapproved plain hose solely to recover spray. Cross-connection prevention addresses why backflow protection is a separate concern from comfortable flow.
Confirm the connection parts with water off
Turn the shower off and follow the model's instructions before loosening any connection. Waterpik's FAQ also lists a washer left from the old shower as a possible post-installation obstruction, and describes its specified screen and washer arrangement. Check the actual instructions rather than adding washers until a leak stops.
Do not discard screens, flow-control parts or backflow devices to improve output. If a component is stuck, the connection is damaged or the shower arm moves inside the wall, stop and obtain qualified help. Do not force the arm or open the wall valve's internals for a hose check.
Verify the correction without assuming a complete diagnosis
After the approved arrangement is restored, use the documented test and inspect accessible connections for leakage. A hose that now passes water still needs a secure, compatible installation. Waterpik directs owners to stop using a damaged or malfunctioning product and contact support.
Hand-shower connection leaks are a different symptom. Gradual nozzle restriction has its own cleaning investigation. If normal flow remains absent after the verified hose checks, report the model, replacement part, end labels and installation history alongside other low-flow observations. That gives support or a plumber a concrete starting point without defeating protection or treating every weak shower as scale.