[8-K] CALIFORNIA WATER SERVICE GROUP Reports Material Event

Rhea-AI Filing Summary

California Water Service Group, through its California regulated utility subsidiary Cal Water, reports that the California Public Utilities Commission has granted Cal Water and three other Class A water companies an additional one-year extension for their joint cost of capital filing deadline to May 1, 2027. The existing Water Cost of Capital Mechanisms will remain in effect during this extended period, meaning the current regulatory framework for determining returns on investment stays in place for longer. The company also issued a press release to announce this extension.

Insights

Regulated Utilities Analyst

Regulator granted a one-year cost of capital filing extension; current mechanisms stay in place through at least May 1, 2027.

The filing reports that the California Public Utilities Commission granted **California Water Service Company** and three peer Class A water utilities a one-year extension for their next **cost of capital** filing to May 1, 2027. During this period, the existing **Water Cost of Capital Mechanisms** remain in effect. In simple terms, this means the current regulatory formula that sets the allowed return on equity and related capital structure continues without reset for an extra year.

This extension reduces near-term regulatory uncertainty around the company’s authorized return, since no new cost of capital proceeding is required until the new deadline. The continued operation of the Water Cost of Capital Mechanisms suggests that any adjustments to returns will keep following the established framework instead of being renegotiated from scratch. That tends to stabilize earnings drivers that depend on the allowed return and capital costs.

The key item to track is how long the existing cost of capital terms and adjustment mechanism remain unchanged and whether any future filing by May 1, 2027 proposes meaningful revisions. Attention also naturally turns to how the mechanism functions during the extension period under different interest rate environments, because that can influence allowed returns within the current structure. The attached press release in Exhibit 99.1 offers the company’s public framing of this extension.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

Current Report Pursuant to Section 13 or 15(d) of
The Securities Exchange Act of 1934

Date of Report (date of earliest event reported): November 18, 2025

CALIFORNIA WATER SERVICE GROUP

(Exact name of Registrant as Specified in its Charter) 

Delaware
(State or other jurisdiction
of incorporation) 1-13883
(Commission file number) 77-0448994
(I.R.S. Employer
Identification Number)

1720 North First Street
San Jose, California
(Address of principal executive offices) 95112
(Zip Code)

(408) 367-8200

(Registrant’s telephone number, including area code)

N/A

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
¨	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
¨	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
¨	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Shares, par value $0.01		CWT		New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined by Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 8.01. Regulation FD Disclosure.

On November 18, 2025, California Water Service Company, the Registrant’s California regulated utility subsidiary (“Cal Water”), received a letter from the California Public Utilities Commission (the “CPUC”) addressed jointly to Cal Water and three other Class A water companies (California-American Water Company, Golden State Water Company, and San Jose Water Company, collectively with Cal Water, the “Joint Parties”), granting the Joint Parties’ request for an additional one-year extension in their cost of capital filing with the CPUC to May 1, 2027. The Water Cost of Capital Mechanisms will remain in effect during the one-year extension.

On November 20, 2025, California Water Service Group issued a press release (a copy of which is attached hereto as Exhibit 99.1 and incorporated herein by reference) announcing the cost of capital filing extension.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

We hereby file the following exhibit with this report:

Exhibit No.		Description
99.1		Press Release issued November 20, 2025
104		Cover Page Interactive Date File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	CALIFORNIA WATER SERVICE GROUP
Date: November 20, 2025	By:	/s/ James P. Lynch
	Name:	James P. Lynch
	Title:	Senior Vice President, Chief Financial Officer and Treasurer

FAQ

What did California Water Service Group (CWT) announce in this 8-K?

California Water Service Group disclosed that its subsidiary Cal Water received approval from the California Public Utilities Commission for a one-year extension of its joint cost of capital filing deadline to May 1, 2027, with existing Water Cost of Capital Mechanisms remaining in effect.

Who granted the cost of capital filing extension to CWT's subsidiary?

The California Public Utilities Commission (CPUC) granted the extension to Cal Water and three other Class A water companies in response to their joint request.

Which companies are included with Cal Water in the joint cost of capital filing?

The joint parties include Cal Water, California-American Water Company, Golden State Water Company, and San Jose Water Company.

How long is the cost of capital filing deadline extended for CWT's Cal Water unit?

The filing deadline is extended by one year, moving the due date for the joint cost of capital filing to May 1, 2027.

What happens to the Water Cost of Capital Mechanisms during the extension period?

The Water Cost of Capital Mechanisms will remain in effect throughout the one-year extension, maintaining the current approach for setting Cal Water’s authorized cost of capital.

Did California Water Service Group issue a press release about the CPUC extension?

Yes. California Water Service Group issued a press release dated November 20, 2025, attached as Exhibit 99.1, announcing the cost of capital filing extension.