The water pressure in the shower is very low.
pres-SIO-ne — three syllables, stress on the second.
Report low water pressure to reception. It can sometimes be improved by adjusting valves — a maintenance person can often fix it quickly.
'Pressione dell'acqua' = water pressure. 'Bassa' (low, feminine) agrees with 'pressione' (feminine). 'Molto bassa' = very low. This is a common complaint in older Italian buildings where pipes are narrow and shared across multiple floors.
La doccia a malapena funziona.
The shower barely works.
A more emphatic description of very low pressure
L'acqua esce a gocce.
The water comes out in drops.
The most extreme form of low pressure
Di mattina la pressione è migliore?
Is the pressure better in the morning?
Pressure can be higher at off-peak hours — ask if this is the case
Old Italian piping systems ('impianti idraulici') in historic buildings were designed for far fewer users than modern hotels accommodate. Shower pressure peaks are usually between 6–8am and then again after 8pm. If you have a choice, shower at these times for the best pressure.