NZ Plumbers' Merchants Society Ltd (NZPMS) started off as the brainchild of a group of like-minded master plumbers who were unhappy with the delivery of products and services from the plumbing merchants and wholesale plumbers guild.

In 1962, dissatisfied master plumbers explored the co-operative model to address issues with plumbing merchants. A panel of directors was established in 1962, initiating inquiries to acquire a Palmerston North plumbers' merchant. On 1 September 1964, the official purchase of shares in Shand Brothers Ltd, Palmerston North, allowed the group to trade. The purchase also involved 1/3 holdings in a Shand Family Trust subsidiary, Metalcraft Industries Ltd of Palmerston North and manufacturers of plumbers requisites in stainless steel, copper and galvanised iron. On September 28, 1964, the Master Plumbers Merchants Society Ltd was registered (later renamed NZ Plumbers Merchants Society Ltd), with the drafting of a constitution and the appointment of directors.

"Master Plumbers' Co-operative takes over leading Plumbers' Merchants as first step towards establishing Dominion Merchants' Chain." NZ Plumbers Journal Sep 1964.

• 1965 — Ido De Bernardo voted in as Chairman.
• 1965 — The first Branch Manager & Board of Directors meeting took place.
• 1966 — Head Office established in Palmerston North.
• 1966 — The Wellington branch operated the store with a staff of 2 and a 1959 flat-top Bedford truck was purchased. The Bedford was a great asset because the NZPMS branch was one of the only outlets in Wellington to offer a delivery service.
• 1968 — The first custom-built branch in Mackelvie St, Auckland.
  
• 1968 — Five branches, 437 shareholders and fifty staff members.

• Between 1969 - 1970s — 10 more branches opened
• Mid 70s — 6 branches had reached $1 million in sales for the year.
• 1978 — Graded Rebate system introduced
• 1979 — "A Grade" was paid on current debt payment at 12.5%
• End of 70s - All 15 branches had reached $1 million in sales for the year with 3 reaching $2 million.

"Looking back the biggest shift came in 1988 with deregulation of the economy. Till then we were committed to the philosophy of orderly trading for the benefit of the Master Plumbers. That changed and in its place, we have become competitive traders. However, obviously the plumber/shareholder remains at the forefront of our planning decisions." Managing Director Paul Cowan 1993.

• 1988 — Removal of restrictions meant Plumbing World could buy directly from importers as well as manufacturers.
• 1988 — Our first overseas trip promotion. This was originally planned as a trip with about 400 people to a convention in Surfers Paradise and a visit to the Expo site, but the response was so positive that more than 700 plumbers and their wives went to Brisbane as part of the Plumbing World Expo promotion.
• 1989 — April 1 marked the end of the Society as it renamed itself as NZ Plumbers' Merchants Ltd (NZPM), and all trading operations were now undertaken by Plumbing World.

The Overseas Trips Programme continued and shareholders enjoyed trips to Los Angeles and Las Vegas (1990), Thailand (1991), Gold Coast (1993), Canada (1995), New Orleans (1997) and Perth (1999).

• 2001 — Plumbing World branches were painted purple and a new logo with icons representing the four business sectors was introduced.
• 2004 — The 40-year anniversary of NZPM was celebrated with record sales of $183 million, and record trading profits of $10.6 million.
• 2005 — NZPM purchased 30% of Aquatherm.
• 2007 — Inovo opened, Metrix was purchased (more info below), 12.5% of Construction Marketing Services was purchased in July, Patten Aero was established in Thailand, Patton Central Queensland was established in October, Patton India in November and Mellcott Refrigeration, with branches at Bendigo and Ballarat in Australia was purchased in February 2008.
• 2008 — NZ Plumbers' Merchant Ltd changed to NZPM Group Ltd. Because of the increasing importance of the Patton side of the business it was felt that the new name better reflected the Group nature of the parent company. It was also important because the "old" name was causing confusion overseas with the inclusion of "Plumbing Merchants" in the name.
• Overseas Trips Programme continued Gold Coast (2001), London (2002) Nadi, Fiji (2003), Egypt (2004), Port Douglas (2005), then every two years with trips to San Francisco (2007) and Vietnam (2009).

Metrix was purchased by NZPM in July 2007. It had been a privately owned company with a warehouse in Albany and a retail outlet at Newmarket, Auckland. It was purchased to provide Plumbing World with a conduit for exclusive, mostly European, products. In all, Metrix held 17 agencies including the Duravit brand and 18 staff with an average of 8 years service in the company. Many of their products had been sold through rival plumbing merchants so it was mostly all new business for Plumbing World. Garry Ivill was appointed General Manager and quickly set about getting Metrix products set up and established throughout Plumbing World branches.

Product names such as Kaldewei, Duravit, Dornbracht, Paini, Inda, and Valsir quickly became an integral part of Plumbing World stock items.

• 2010 — Plumbing World gained the exclusive agency for the bathroomware brand Toto in 2010.
• 2010 — Ido Debernado passed away in November 2010 at 90 years of age. Ido had been a true champion of the industry not just in words but also in deeds.
• 2011 — Rob Kidd was appointed General Manager of Plumbing World, following the resignation of Kevin Smith.
• 2012 — Young Plumbers Club established.
• 2013 — John DeBernado replaced Paul Smart (2011-2013) as Chair, with Paul becoming deputy Chair.
• 2013 — In December, Plumbing World were thrilled to sign up Legendary All Black No.8 Kieran Read as brand ambassador.
• 2015 — Divestment in Patton Shareholding.
• 2017 — Young Plumber of the Year established. YPOTY annual competition showcases and rewards the best and brightest in the industry.
• 2017 — NZPM established the Future Governance Programme to foster future elected director capability from within our ordinary shareholder membership pool, through a formal training and mentoring programme.
• 2018 — Redevelopment of the Plumbing World retail website.
• 2018 — Divestment in Aquatherm and CMS Shareholding.
• 2018 — NZPM acquired a commercial property in Kingsland, Auckland. Kingsland would replace the Grey Lynn branch premises when the lease would end in 2020.
• Overseas Trips continued with Buenos Aires (2011), New York (2013), Singapore (2015), Rome (2017), Fiji (2018).
• 2019 — pwGO Trade App Launch in August.
• 2019 — Plumbing World moved into the new Distribution Centre (DC) in Wiri, South Auckland, during June. Metrix moved in during September.

• 2020 — The country reached Level 4 response to the Covid 19 outbreak. NZPM companies responded well, by abiding by all government regulations and sourcing PPE for our customers and staff. We assisted Master Plumbers in lobbying for change to get all plumbing products listed as ‘essential’ so building work could continue throughout NZ during the various alert level changes.
• 2020 — NZPM acquired a one-third shareholding in Aqua Source & QC Co., Limited (Aqua Source), a company incorporated in Hong Kong.
• 2020 — Merged a number of the internal functions of Plumbing World and Metrix such as finance, technology, warehousing, freight and health & safety.

• 2022 — Plumbing World Helps Website was developed. A marketing initiative that gives homeowners inspiration on their renovation journey.

• 2023 — John DeBernardo (Chair) passed away on 18 April after a 15-month battle with cancer. While John’s father was instrumental in establishing our great co-operative 59 years ago, John himself joined the NZPM Board just over 12 years ago and became Chair almost 10 years ago.
• 2023 — John's long-standing contribution to NZPM was acknowledged as recipient of a Lifetime Achievement Award from the Cooperative Business NZ Board (NZCOOP), recognising individuals who give of themselves freely to the cooperative and mutual community.
• 2023 — Appointment of Katherine (Kathy) Meads as Chair.
• 2023 — Company name change from ‘NZPM Group Limited’ to ‘NZPM Co-operative Limited’. We believe this change of company name better aligns with our co-operative structure and ethos, and also reflects a simple change to a brand — NZPM Co-operative.
• 2023 — DTS (direct-to-site) operation established in Porirua to service the greater Wellington region. Through taking this step we aim to reduce the current burden on the local branches, streamline our inventory position and optimise and freight offer to the market.
• 2023 — Metrix/NZPM relocates to 65 Parnell Rise, Parnell, Auckland 1052.