🏢 Early beginnings Origins: Neptun Foundry, Breslau (1862–1912)

Diehl Metering traces its roots to Neptun, a foundry established in 1862 in Breslau (now Wrocław, Poland).

Neptun produced fittings for water and gas installations and, in 1895, developed the world’s first Woltmann bulk water meter — a breakthrough that became the global standard for high‑flow metering. The company is one of Europe’s oldest metering lineages (1862 → present).

Hydrometer Era (1912–1951)

In 1912, Neptun was renamed Hydrometer – Breslauer Wassermesserfabrik, marking its evolution into a specialist manufacturer of:

- Domestic water meters

- Industrial Woltmann meters

- Calibration and verification equipment

Hydrometer became a respected German brand known for precision engineering and durable brass and cast‑iron construction.

Relocation to Ansbach, Bavaria (1951)

After World War II, Hydrometer relocated to Ansbach, Bavaria, where it established a modern production centre that remains a core Diehl Metering facility today.

Key milestones:

1970 — One‑millionth water meter produced in Ansbach

1989 — PTB accreditation for an electronic flow‑meter module

1991 — Hydrometer Group formed; new mass‑production plant opened in Apolda (Thuringia)

Innovation & Expansion (1990s–2000s)

Hydrometer became a European leader in metering technology, pioneering:

- Ultrasonic metering (development began 1991)

- IZAR radio technology (1996), enabling remote meter reading

- Electronic and hybrid metering systems

In 1998, Hydrometer expanded through strategic acquisitions:

- Sappel (France) — domestic water meters & radio systems

- Mirometr (Poland) — meter production and regional distribution

These additions created a unified European metering group.

Integration into Diehl Group → Diehl Metering (2000s–Present)

Hydrometer became part of the Diehl Group, a major German technology conglomerate.

Today, Diehl Metering is a global leader in:

- Water and heat meters

- Ultrasonic metering

- IoT and AMI systems

- IZAR radio and data‑analytics platforms

- Smart‑city and utility‑network solutions

Corporate Lineage

Neptun (1862, Breslau)

→ Hydrometer (1912)

→ Hydrometer Group (1991)

→ Acquisition of Sappel & Mirometr (1998)

→ Diehl Group (Metering Division)

→ Diehl Metering (modern global brand)

🏭 Factory Locations (Historical & Modern)

- Breslau / Wrocław (1862–1951) — Neptun / Hydrometer origins

- Ansbach, Bavaria (1951–present) — Main HQ & production

- Apolda, Thuringia (from 1991) — Mass production of domestic meters

🧰 Product Evolution 19th Century;

- Fittings for water & gas

- Early mechanical meters

- World’s first Woltmann meter (1895)

20th Century;

- Domestic water meters

- Industrial Woltmann meters

- Electronic flow‑meter modules

- Calibration & testing systems

21st Century;

- Ultrasonic water & heat meters

- IZAR radio / IoT systems

- Smart‑metering platforms

- Data‑analytics & leakage detection The Museum has a 20mm ultrasonic Diel Hydrus meter in its collection shown bottom left.