Domakihub How to Install a Shower Pump and Boost Weak Water Pressure
A step-by-step guide for low-pressure homes, holiday rentals, and hotel rooms in Greece.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
Weak shower pressure is one of the most common complaints in older Greek apartments, island villas, and holiday rentals that rely on rooftop storage tanks rather than mains pressure. A shower pump sits between your cold-water tank or hot-water cylinder and the shower head, boosting flow so guests and residents actually enjoy the shower. The video above walks through real installation and the mistakes to avoid; the steps below give you the full picture so you know exactly what the job involves — and when to hand it to a licensed plumber.
Why Rooftop Tanks Create Low Shower Pressure
Most buildings in Greece store water in a rooftop cistern (δεξαμενή) and rely on gravity to push water down to each floor. The further the shower is from the tank — or the more residents sharing the system — the weaker the pressure becomes. A shower pump compensates by actively drawing water from the supply and pushing it to the shower head at a consistent bar rating.
Twin-impeller pumps boost both the hot and cold feeds simultaneously, which prevents unwanted temperature swings when flow is increased. Single-impeller pumps handle one feed only and suit simpler setups where only the cold or the hot side needs help.
Choosing the Right Pump
Bar rating matters: 1.5 bar is adequate for most homes; 2.0–3.0 bar suits properties where the tank sits less than 1 metre above the pump or where multiple shower heads run at once (hotels, large villas). Always measure the static head — the vertical distance in metres between the base of the cold-water tank and the pump — before buying. Too little head and the pump cavitates; too much bar for the pipework and joints will leak.
Brand reliability is worth paying for in Greece's salt-air coastal climate. Stuart Turner, Grundfos, and Salamander are the most widely stocked; check that spare parts and service agents are available in your region before committing to a model.
How to Install a Shower Pump: 5 Steps
- 1
Turn off the water supply and drain the pipes
Shut the isolator valve on the cold-water feed from the tank and the gate valve on the hot feed from the cylinder. Open the existing shower to drain residual pressure. Lay towels and have a bucket ready — even after draining, pockets of water remain in horizontal runs and will spill when you cut pipes.
- 2
Position and secure the pump body
Mount the pump on a firm, vibration-damping surface — a piece of dense rubber mat on a shelf or the bathroom floor works well. Keep the pump as close as possible to the hot-water cylinder or cold-tank outlet; long inlet runs increase the risk of cavitation (air entering the pump). The pump must sit below the level of both the cold tank base and the hot cylinder connection so water feeds by gravity before the pump kicks in. Follow the manufacturer's minimum static-head requirement exactly.
- 3
Connect the inlet and outlet pipework
Use flexible braided hoses on both inlet ports (hot and cold for a twin pump) to absorb vibration and prevent noise transmission through the walls. Fit non-return valves on both inlets if they are not built into the pump — these stop back-siphoning that can mix hot and cold water inside the pump body. Apply PTFE tape to all male threads and hand-tighten fittings before a quarter-turn with a wrench; over-tightening cracks pump bodies. Connect the pump outlet to the shower supply pipe using copper or plastic push-fit rated to the pump's pressure.
- 4
Wire the electrical connection — licensed electrician required
A shower pump runs on a standard 230 V supply but must be installed by a licensed electrician (αδειούχος ηλεκτρολόγος) in compliance with Greek electrical regulation (ΚΕΗΕ). The pump must be on a switched fused spur (not a plug socket) and positioned outside IP-zone restrictions — typically at least 0.6 m from the shower enclosure boundary. The electrician will also verify earth continuity and bonding of all metal pipework, which is mandatory. Do not attempt this step yourself.
- 5
Restore water supply, prime the pump, and test
Open the inlet valves slowly to let water fill the pump chamber without trapping air. Most pumps self-prime, but you may need to briefly run the hot and cold taps on the basin nearest the cylinder to purge air from the hot feed first. Turn on the shower: the pump should start within 2–3 seconds of flow being detected (flow-activated models) or when you flip the manual switch. Check all connections for drips under pressure, and listen for rattling — tighten any loose fittings and adjust the rubber mounts if vibration noise carries through the floor or walls.
Rather have a pro handle it?
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FAQ
- Do I need a plumber to install a shower pump in Greece?
- The plumbing connections — pipework, hoses, and valves — can legally be completed by a competent DIYer in Greece, but the electrical spur that powers the pump must be wired by a licensed electrician (αδειούχος ηλεκτρολόγος). For rented properties and hotels, landlords are also expected to use certified tradespeople to ensure insurance validity.
- Can a shower pump work with a combi boiler or mains-pressure system?
- No. Shower pumps are designed exclusively for gravity-fed (low-pressure) systems that use a separate cold-water storage tank and a vented hot-water cylinder. Installing a pump on a combi boiler or unvented pressurised system will damage both the pump and the boiler and may void warranties. If you have a combi boiler and low pressure, the fix is to investigate the boiler's pressure settings or the main supply — not to add a pump.
- Why is my new shower pump noisy or vibrating?
- The three most common causes are: (1) air in the system — prime the pump by running taps until air is fully purged; (2) the pump is mounted on a hard surface without damping — place a rubber mat underneath and use flexible hose connectors; (3) cavitation caused by insufficient static head — if the tank sits too close to the pump level, water cannot gravity-feed fast enough and the pump draws in air. Check the manufacturer's minimum head requirement and raise the tank or lower the pump if needed.