Water-Saving Showerheads and Flow Restrictors

Replacing showerheads and tap aerators with water-saving versions (6-9 l/min instead of 12-18 l/min).

How do low-flow showerheads and flow restrictors work?

A conventional showerhead passes 12 to 18 litres of water per minute. Low-flow showerheads mix air into the water jet or swirl it, so that 6 to 9 l/min is enough to maintain the spray pattern and the showering experience. Flow restrictors and aerators on basin taps work on the same principle and limit the flow rate regardless of line pressure. Because less hot water is drawn on every shower, energy demand for hot water production drops immediately, as do the costs for drinking water and wastewater. Replacement is done without tools at the standard G½ connection and takes a few minutes per outlet, which is why the measure can be implemented in occupied buildings without disruption.

Which buildings benefit from low-flow showerheads?

The measure works wherever a lot of showering takes place: multi-family houses, hotels, care homes, schools with sports facilities and sports venues. Existing standard showerheads with a G½ connection are the prerequisite. Replacement is not worthwhile if low-flow heads are already installed or if special installations such as spa facilities require a specific flow rate. With very low line pressure or instantaneous water heaters with a minimum flow rate, suitability must be checked case by case. In rental properties acceptance is high, because residents see the effect directly on their water bill and comfort is maintained.

What do low-flow showerheads actually deliver?

Hot water demand falls by 30 to 50 %. The energy saving is calculated from the number of users, shower duration, flow rate reduction, temperature difference between cold and hot water and the efficiency of the hot water system. A multi-family house with 50 residents saves around 30,500 kWh/a of heat and roughly 6.1 t CO2 at 6 minutes of showering per day and a 6 l/min lower flow rate, plus the corresponding volume of drinking water. Costs are €8 to €30 per showerhead and €3 to €12 per aerator. Payback is under a year, often under six months, with a service life of around 8 years. This makes the measure one of the most economical of all.

Energy carrier

Erdgas, Heizöl, Strom, Fernwärme → Erdgas, Heizöl, Strom, Fernwärme

Savings potential

30-50 % WW-Bedarf

Worked example

A multi-family house with 50 residents is supplied by a gas boiler that produces hot water at an efficiency of 0.75. The existing standard showerheads are replaced with low-flow heads, reducing the flow rate by 6 l/min. A shower time of 6 minutes per person per day and a 30 K temperature difference between cold and hot water are assumed. The saving is calculated as E_saved = 50 × 6 × 6 × 1.163 × 30 / 0.75 × 365 / 1,000 = 30,561 kWh/a. The building therefore saves around 30,500 kWh of heat per year and roughly 6.1 t CO2; on top of that come 6,570 m³ of drinking water that neither need to be treated nor disposed of. At a cost of €8 to €30 per showerhead, the replacement pays back in less than a year. Hot and cold water meters per apartment show the effect immediately in a before-and-after comparison.

Investment & payback

8-30 €/Brausekopf, 3-12 €/Strahlregler · Service life: 8 a · Payback: <1 a

Applicability

Requirements

Exclusion criteria

Typical buildings

Frequently asked questions

How much water and energy does a low-flow showerhead save?

A low-flow showerhead reduces the flow rate from 12 to 18 l/min to 6 to 9 l/min and cuts hot water demand by 30 to 50 %. A multi-family house with 50 residents saves around 30,500 kWh of heat per year at 6 minutes of showering per day. Since hot water is a significant part of energy consumption, the saving feeds directly through to heating, water and wastewater costs.

How much does a low-flow showerhead cost and when does it pay back?

A low-flow showerhead costs €8 to €30; an aerator for basin taps costs €3 to €12. Payback is under a year, often under six months in properties with heavy shower use. With a service life of around 8 years, the replacement is one of the most economical energy-saving measures in a building and requires neither tools nor specialist staff.

Can you notice the difference when showering with a low-flow head?

Modern comfort low-flow showerheads mix air into the water, so the spray stays full and pleasant despite 6 to 9 l/min. The difference from a standard showerhead is barely noticeable in everyday use. Simple flow restrictors without air injection, on the other hand, can produce a noticeably thinner jet. With instantaneous water heaters, the minimum flow rate of the appliance must be observed.

What is the difference between a low-flow showerhead and a flow restrictor?

A low-flow showerhead is a complete shower head with integrated air injection or swirl technology that maintains the spray pattern at a lower flow rate. A flow restrictor is a small insert screwed in between hose and showerhead or fitted as an aerator in the tap, limiting the flow rate independently of pressure. Both achieve similar savings; the low-flow showerhead usually offers greater comfort.

Are there standards for showerhead flow rates in Austria?

The requirements for showerheads are set out in EN 1112, which among other things defines flow classes and leak tightness. ÖNORM EN 246 applies to aerators on taps. Products marked to these standards state their nominal flow rate, so the saving compared with the existing showerhead can be calculated in advance. In Austria, the Umweltberatung environmental advisory service recommends flow restrictors as a low-cost immediate measure.

Related measures

Standards & sources

Metering points in the EDM Toolbox

Direkter Messpunkt: Warm- und Kaltwasserzähler. Vergleich vor/nach via Submetering pro Wohnung möglich - klassischer EDM-Use-Case mit hoher User-Akzeptanz (Mieter sehen direkten Effekt).

All measures