The verdict in three sentences
An inter-municipal water utility with 22,000 customers whose billing software is reaching end of life should budget 80,000 to 150,000 EUR excl. VAT for a package or 90,000 to 140,000 EUR for custom development. The scope expected in 2026 includes mobile meter reading, monthly direct debit, a customer portal and an interface with the public Treasury (Hélios in France), for a project of about 8 months. Data migration and synchronisation with the public accountant decide success far more than the choice of vendor.
Package or custom: five-year total cost
The market for municipal water billing software is concentrated among a few vendors. Their packages are proven, but every adaptation (seasonal tariff, sewerage share billed for another authority, water agency levies) becomes a billable service.
| Item (5 years, 22,000 customers) | Vendor package | Custom development |
|---|---|---|
| Licence or initial development | 80,000 to 150,000 EUR | 90,000 to 140,000 EUR |
| Annual maintenance | 15 to 18 % of licence, so 12,000 to 27,000 EUR | 10,000 to 15,000 EUR |
| Migration from legacy software | often extra, 8,000 to 15,000 EUR | included |
| Tariff or regulatory change | 1,500 to 4,000 EUR per request | included in regular maintenance |
| Code ownership and reversibility | licence, export to negotiate | code and data owned by the utility |
| Estimated 5-year total cost | 150,000 to 300,000 EUR | 140,000 to 215,000 EUR |
Depending on the amount, procurement is either a simplified procedure or a formal tender: the EU threshold for local authorities is around 216,000 EUR excl. VAT in 2026, calculated over the full contract term, maintenance included.
Functional scope and custom budget
| Module | Content | Indicative budget |
|---|---|---|
| Customers and contracts | connections, meters, move-ins and move-outs, history | 14,000 to 20,000 EUR |
| Mobile meter reading | routes, offline entry, photos, anomalies | 12,000 to 18,000 EUR |
| Billing and tariffs | fixed charge, tiers, sewerage, levies, 5.5 % and 10 % VAT | 18,000 to 28,000 EUR |
| Monthly payments | schedule, SEPA direct debit, annual true-up | included in billing |
| Treasury interface | PES V2 flows for bills and payment notices, PayFiP online payment | 12,000 to 18,000 EUR |
| Customer portal | bills, online meter readings, direct debit, requests | 14,000 to 22,000 EUR |
| Collections | reminders, payment plans, solidarity fund support | 8,000 to 14,000 EUR |
| Migration, testing, training | parallel control billing on one route | 12,000 to 20,000 EUR |
| Total | 90,000 to 140,000 EUR |
The Treasury interface is the most sensitive point: each billing run must be accepted by the public accountant without rejection, and receipts must flow back into the software to track arrears customer by customer.
An 8-month migration plan
| Phase | Duration | Deliverable |
|---|---|---|
| Scoping, tariffs, billing rules | month 1 | approved configuration file |
| Customers, contracts, trial migration | months 2 and 3 | migrated and checked database |
| Billing, monthly payments, mobile reading | months 3 to 5 | compliant test bills |
| Treasury interface and tests | months 5 and 6 | PES V2 flows accepted |
| Parallel billing on one route | month 7 | variance under 0.1 % |
| Cutover, customer portal, training | month 8 | go-live |
Cutover ideally follows a half-yearly billing run, to avoid migrating in the middle of a meter reading campaign.
Mini case study
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Sophie, finance and administration director of an inter-municipal utility near Annecy, bills 22,000 customers for revenue of about 9.24 million EUR. Mobile reading removes 2 minutes of re-keying per meter, so 733 hours and 27,870 EUR a year at 38 EUR per hour. With 40 % of customers switched to e-billing, she saves 2 mailings a year at 1.30 EUR, so 22,880 EUR. Monthly payments and automatic reminders bring arrears down from 3.5 % to 2.5 %, so 92,400 EUR recovered. The custom project chosen at 118,000 EUR pays back in under 10 months.
FAQ
What does billing software cost for a 22,000-customer water utility?
Plan on 80,000 to 150,000 EUR for a package and 90,000 to 140,000 EUR for custom. Over five years, maintenance included, the envelope is 140,000 to 300,000 EUR.
Is the Hélios interface mandatory?
Yes for a French utility with a public accountant: bills and payment notices travel in PES V2 format. Allow 4 to 6 weeks of testing with the Treasury before cutover.
How long does migration take?
About 8 months, including one month of parallel billing on a route to check variances. A variance above 0.1 % blocks cutover.
Can water be cut off for non-payment?
Not for a main residence in France, the Brottes law forbids it all year. The software must rely on monthly payments, graduated reminders and payment plans, which cut arrears by about one point.
Do customers really use the portal?
At a utility of this size, 30 to 45 % of customers create an account within two years, mainly for direct debit and PayFiP online payment.
Let's scope your project. Send us your customer count, current software and meter reading calendar: we will price a migration between 90,000 and 140,000 EUR over 8 months. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.