The aim of this clinical trial is to learn whether a thirst-driven, liberal fluid-intake strategy is comparable to a fluid-restriction strategy in patients hospitalized for acute decompensated heart failure (ADHF). The study will also assess the safety of the intervention and its effects on thirst and quality of life.

Patients hospitalized with ADHF will be asked to follow either a thirst-driven fluid-intake strategy or a fluid-restriction strategy during their hospital stay and for one month after discharge.

Inclusion Criteria:

1. Age >18 years

2. Hospitalized for ADHF as the primary diagnosis, meeting both of the following:

   1. ≥1 documented symptom of new or worsening heart failure (dyspnea, fatigue, decreased exercise tolerance, or symptom of end-organ hypoperfusion).
   2. Objective evidence of ADHF, defined as either:

   i. ≥2 physical signs (edema, ascites, pulmonary rales/crackles, increased JVP, S3 gallop, rapid weight gain due to fluid retention), OR ii. ≥1 physical sign AND ≥1 laboratory finding indicative of ADHF (BNP >500 ng/L or NT-proBNP >2000 ng/L if sinus rhythm, or BNP >750 ng/L or NT-proBNP >3000 ng/L if atrial fibrillation, radiological/ultrasound evidence of pulmonary congestion, echocardiographic sign [VCI >2.1 cm, LVOT VTI <15 cm, E/e' >14, D-dominant pulmonary venous inflow pattern], or invasive evidence [CVP >12 mmHg, PCWP >18 mmHg, CI <2.2 L/min/m2]).

3. Treatment with ≥40 mg IV furosemide (or equivalent)

4. Enrolment within 24 hours of admission

5. Ability to provide informed consent

Exclusion Criteria:

1. Requirement at admission for ICU-level care, or IV inotropic/vasopressor therapy for ADHF.
2. Na+ <125 mmol/L or Na+ >145 mmol/L.
3. End-stage chronic kidney disease on chronic dialysis or eGFR <15 mL/min/1.73 m2
4. Any condition which would make participation unsafe or substantially affect protocol adherence, as judged by investigator.

Due to regulations by Region Committees on Health Research Ethics