Exhibit 8.1

2001 ROSS AVENUE DALLAS, TEXAS 75201-2980   TEL +1 214.953.6500 FAX +1 214.953.6503 BakerBotts.com ABU DHABI AUSTIN BEIJING BRUSSELS DALLAS DUBAI HONG KONG HOUSTON LONDON MOSCOW NEW YORK PALO ALTO RIO DE JANEIRO RIYADH WASHINGTON

February 18, 2014

Regency Energy Partners LP

2001 Bryan Street, Suite 3700

Dallas, Texas 75201

Ladies and Gentlemen:

We have acted as counsel to you in connection with (i) the transactions (the “Transactions”) contemplated by the Agreement and Plan of Merger, dated as of October 9, 2013, and amended on November 7, 2013, (as amended, the “Merger Agreement”) among Regency Energy Partners LP, a Delaware limited partnership (the “Partnership”), Regency GP LP, a Delaware limited partnership and the general partner of the Partnership, RVP LLC, a Delaware limited liability company and a wholly-owned subsidiary of the Partnership, PVR Partners, L.P., a Delaware limited partnership (“PVR”), and PVR GP, LLC, a Delaware limited liability company and the general partner of PVR and (ii) the preparation of the registration statement on Form S-4 (File No. 333-192184), as amended (the “Registration Statement”), filed with the Securities and Exchange Commission (the “Commission”) by the Partnership relating to the Transactions. In connection therewith, you have requested our opinion regarding certain U.S. federal income tax matters relating to the Partnership and its common unitholders.

In preparing our opinion, we have examined the Merger Agreement and the Registration Statement, including the proxy statement/prospectus that forms a part of the Registration Statement. In addition, we have examined such other documents, instruments and information as we considered necessary to enable us to express this opinion. Our opinion is also based on (i) the accuracy of the representations, statements, and facts concerning the Transactions set forth in the Merger Agreement and the Registration Statement (including, without limitation, their respective exhibits) and we have assumed that such representations, statements, and facts will be accurate and complete as of the closing date of the Transactions (as if made as of such time), (ii) the consummation of the Transactions in the manner contemplated by, and in accordance with the terms set forth in, the Merger Agreement and the Registration Statement, (iii) representations made by you with respect to certain factual matters, including the representations set forth in a letter from you, and we have assumed that such representations will be accurate and complete as of the closing date of the Transactions (as if made as of such time), and (iv) financial information provided to us by you.

Based on the foregoing, unless otherwise noted in such discussions, the description of the law and the legal conclusions with respect to matters of U.S. federal income tax law set forth in the discussions in the Registration Statement under the captions “Material U.S. Federal Income Tax Consequences of the Merger—Tax Consequences of the Merger to

Regency Energy Partners LP

Regency and Its Unitholders” and “Material U.S. Federal Income Tax Consequences of Regency Common Unit Ownership” constitutes our opinion. No opinion is expressed as to any matter not discussed herein.

Our opinion is based on the Internal Revenue Code of 1986, as amended (the “Code”), the legislative history with respect thereto, rules and regulations promulgated thereunder, published rulings and court decisions, all as in effect and existing on the date hereof, and all of which are subject to change at any time, possibly on a retroactive basis. There can be no assurance that our conclusions will not be rendered invalid as a result of subsequent changes in the law, including changes to the Code, the regulations thereunder, or the interpretation thereof by the courts or the Internal Revenue Service.

This opinion letter is limited to the matters set forth herein, and no opinions are intended to be implied or may be inferred beyond those expressly stated herein. We assume no obligation to update or supplement this opinion or any matter related to this opinion to reflect any change of fact, circumstances, or law after the effective date of the Registration Statement. In addition, our opinion is based on the assumption that the matter will be properly presented to the applicable court.

We hereby consent to the filing of this opinion with the Commission as an exhibit to the Registration Statement and to the references to our firm and this opinion contained in the Registration Statement. In giving such consent, we do not admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act of 1933, as amended, or the rules and regulations promulgated by the Commission thereunder.

Very truly yours,

/s/ Baker Botts L.L.P.

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