Garden Water Meters: Savings, Verification and Registration

Anyone who regularly waters their garden usually pays twice for that water: once as a fresh-water charge and once as a wastewater fee, even though the water used for watering never enters the sewer system. A garden water meter can eliminate this second charge, but only under two conditions: the municipality must provide for the deduction in its fee bylaws, and the meter must meet certain technical and formal requirements. This article explains what the savings depend on, what “legally verified” means in practice, how installation and registration work, and how meter readings can even help identify problems.

• A garden water meter is installed in addition to the main meter, on a branch line, and records only the water that flows to outdoor taps or the irrigation system.
• Whether and to what extent this affects the wastewater fee is determined by the relevant municipal bylaws, not by a uniform nationwide rate.
• Under Annex 7 of the Measurement and Verification Ordinance (MessEV), cold-water meters must be verified again every six years; otherwise, they lose their validity for billing.
• The meter must be permanently installed and protected from frost; a specialist contractor is generally needed to provide the required separation from the drinking-water installation.
• Anyone who regularly compares the garden and main meter readings can treat an unexplained difference as an early indication of a leak in the outdoor pipework.

Garden water meter: a second meter, not a replacement for the main meter

A garden water meter is not installed instead of the main water meter, but in addition to it, on a branch that runs off downstream of the main meter and leads exclusively to outdoor taps, a garden water connection, or an irrigation system. The main meter continues to measure the total volume of water entering the house and remains the basis for billing drinking water. The garden water meter serves a different purpose: it shows which part of that volume seeps into the ground or evaporates outdoors instead of flowing into the sewer system, thereby providing the basis for deducting exactly that amount from the wastewater fee.

When is a garden water meter really worth it?

Whether the investment pays off depends on three figures that each household needs to know for itself: the actual annual volume of water used in the garden, the local wastewater fee per cubic meter, and the costs of the meter, installation, and subsequent reverification. Whether any deduction is granted at all is also determined by the municipal fee bylaws of the relevant drainage utility, not by uniform national law; without this provision, the meter does not make financial sense, even if it works perfectly.

As a calculation example only, not a promise of savings: Someone who uses around 30 cubic meters of water for irrigation over a gardening season and pays a local wastewater fee of around 3 euros per cubic meter would save about 90 euros in this example year. Over a full six-year verification cycle, that would amount to around 540 euros purely as a calculation, while the meter and professional installation cost around 100 to 240 euros, according to market observations (the meter itself often costs only around 25 euros at a hardware store; professional installation accounts for the larger share). The actual figures will differ depending on garden water use, the fee rate, and the installation circumstances, so it is always worth comparing your own figures and bylaws before buying a meter.

What does “legally verified” mean, and how long is verification valid?

“Legally verified” does not describe a marketing feature, but an accuracy that has been checked as required by law: a verified meter has been tested according to a specified procedure and is allowed to deviate from the actual volume of water that has flowed through it only within strict tolerances. For cold-water meters used for billing, Annex 7, Section 5.5.1 of the Measurement and Verification Ordinance (MessEV) specifies a verification validity period of six years (source: Annex 7, MessEV, gesetze-im-internet.de). After that, the meter may no longer be used for billing, regardless of whether it still displays readings accurately, and must be replaced or verified again. Under Section 5.5.3 of the same annex, electronic add-on devices, such as radio modules for remote reading, are granted a longer validity period of eight years under certain conditions; this applies only to the add-on component, not to the mechanical meter itself.

Installation: a frost-proof, permanently installed meter

For a drainage utility to recognize the meter at all, it must be permanently installed: a removable water meter that can be screwed onto the garden hose and then taken off generally does not meet this requirement, because the measured volume cannot then be reliably attributed to a fixed pipe. The installation location must also be protected from frost, usually in a basement or heated shaft, and not in an exposed outdoor cabinet that freezes in winter. Many utilities also require separation between the drinking-water installation and the garden line, for example with a backflow preventer, so that water from the garden circuit cannot flow back into the drinking-water line (source: Garden water, Dresden Municipal Drainage). Because these requirements can vary from one pipe installation to another and go beyond simply fitting the meter, a specialist contractor usually handles both the installation and advice on the appropriate system separation.

Registering with the water supplier or drainage utility

After installation, the meter must be registered with the responsible water supplier or drainage utility, usually by sending an informal letter or a municipal form requesting the installation date, meter number, and verification date. Some utilities also require meaningful photos of the installation before activating the deduction and checking the details (source: Garden irrigation – intermediate meters, ABN). The obligation does not end with registration: the meter must then be read regularly along with the main meter so that the difference remains verifiable and the deduction continues to apply. For example, Dresden Municipal Drainage requires the property owner to take an annual reading, which must be reported there within two weeks of reading the drinking-water meter (source: Garden water, Dresden Municipal Drainage). This example illustrates the usual general approach, but the specific form, deadline, and any minimum consumption threshold for the registration to be worthwhile at all vary from one municipality to another, so it is sensible to check the bylaws of your own drainage utility before buying.

Comparing meter readings: how a garden water meter can also reveal a leak

Because the garden and main meters measure the same water flow from two different perspectives, comparing them can tell you more than just the amount eligible for deduction. By comparing both meter readings over several reading dates, you can check whether the increase on the main meter is consistent with the recorded garden use. If consumption on the main meter rises significantly more than actual irrigation can explain, that points to a leak somewhere between the main meter and the garden, for example in an underground supply pipe that might otherwise go unnoticed until visible water damage occurs.

This comparison is still a periodic, manual check, and a problem only becomes apparent at the next meter reading. An additional layer is continuous monitoring of the main line itself, described in more detail in the article about smart water leak detectors with shutoff valves. According to the product page, the Smart Whole House Water Leak Detector with automatic shutoff valve is installed on the main line and can automatically shut off the water supply as soon as the measured flow pattern deviates from learned normal usage. An alarm alone does not stop a leak, and no device guarantees that water damage will be completely avoided; installation follows the accompanying instructions and, where they specify, must be carried out by a specialist contractor. The overview of the complete home water system shows how the main line as a whole fits into a well-designed water system, from the supply line to the individual points of use, and anyone who wants to take a closer look at the supply line itself can find background information in the guide to point-of-entry home water filtration.

Frequently asked questions about garden water meters

How much does a garden water meter with installation cost? As a ballpark figure, not a price promise, a legally verified meter costs around 25 euros at a hardware store, while professional installation, including system separation, often costs an additional 75 to 215 euros, depending on the installation circumstances and region. Reverification or a new meter will also be needed later during the six-year verification cycle, and should be included in the same calculation.

Is a regular water meter enough, or does it have to be a legally verified meter? For a deduction from the wastewater fee, drainage utilities require a legally verified, permanently installed, frost-proof intermediate meter; an ordinary, unverified water meter or a removable flow meter on the garden hose is generally not accepted for this purpose, even if it measures accurately.

Each municipality sets out the exact details in its own bylaws: which form applies, what deadline must be met, and from what volume the registration is worthwhile at all. A quick look at the local drainage utility’s website before buying can save you from surprises when it comes to getting the meter recognized. The Hydrion news blog has more explainers about meters and readings.