At the time the homes were built that was sufficient to meet the electrical needs of most homes.With the addition of dishwashers, flat screen tv’s, microwaves, hairdryers, toaster ovens and all the electrical devices we’ve come to depend on 60 or 100 amps is no longer sufficient to support your home’s electric needs.
Refer to Australian/New Zealand Wiring Rules entitled AS/NZS 3007, Electrical Installations (known as the Australian/New Zealand Wiring Rules), as in force from time to time, published jointly by Standards Australia and Standards New Zealand.
Upgrading your electrical service means that you upgrade your electrical system to bring more power into your home.
Many older homes were built with 60 to 100 amps of electrical service.
A few ground wires are connected to the cold-water supply, but I believe that they are for a 240v electrical-baseboard heater system.
Modern circuits are grounded for safety, so your concern is well-founded.