Accounting policies - Investments and Other assets (Details) gal in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) gal	Dec. 31, 2020 USD ($)
Criteria for recognizing investment at cost	Investments where the Company does not exercise significant influence over the operating and financial policies of the investee and holds less than 20% of the voting stock are recorded at cost.
Equity Method Investment, Additional Information	The Company uses the equity method of accounting for investments in common stock where the Company holds 20% to 50% of the voting stock of the investee and has significant influence over its operating and financial policies but does not meet the criteria for consolidation.
Accumulated Amortization of Other Deferred Costs	$ 2,700,000	$ 2,500,000
Amortization of Other Deferred Charges	$ 179,353	179,353
Amount required to reduce the amount of water lost by the public water distribution system | gal	438
Capitalized Engineering Labor and Materials Cost [Member]
Other Assets	$ 3,500,000	$ 3,500,000