diff --git a/water-api/src/services/meter.service.ts b/water-api/src/services/meter.service.ts
index 6e66ccc..6507bf7 100644
--- a/water-api/src/services/meter.service.ts
+++ b/water-api/src/services/meter.service.ts
@@ -81,7 +81,6 @@ export interface Meter {
 export interface MeterWithDetails extends Meter {
   concentrator_name?: string;
   concentrator_serial?: string;
-  project_id?: string;
   project_name?: string;
 }
 
@@ -124,7 +123,7 @@ export interface CreateMeterInput {
   serial_number: string;
   meter_id?: string | null;
   name: string;
-  project_id: string;
+  project_id?: string;  // Optional - will be obtained from concentrator if not provided
   concentrator_id: string;
   location?: string;
   type?: string;
@@ -345,6 +344,21 @@ export async function getById(id: string): Promise<MeterWithDetails | null> {
  * Create a new meter
  */
 export async function create(data: CreateMeterInput): Promise<Meter> {
+  // If project_id is not provided, get it from the concentrator
+  let projectId = data.project_id;
+  if (!projectId) {
+    const concentratorQuery = await query<{ project_id: string }>(
+      'SELECT project_id FROM concentrators WHERE id = $1',
+      [data.concentrator_id]
+    );
+    
+    if (concentratorQuery.rows.length === 0) {
+      throw new Error('Concentrator not found');
+    }
+    
+    projectId = concentratorQuery.rows[0].project_id;
+  }
+
   const result = await query<Meter>(
     `INSERT INTO meters (serial_number, meter_id, name, project_id, concentrator_id, location, type, status, installation_date)
      VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
@@ -353,7 +367,7 @@ export async function create(data: CreateMeterInput): Promise<Meter> {
       data.serial_number,
       data.meter_id || null,
       data.name,
-      data.project_id,
+      projectId,
       data.concentrator_id,
       data.location || null,
       data.type || 'LORA',
@@ -369,6 +383,19 @@ export async function create(data: CreateMeterInput): Promise<Meter> {
  * Update an existing meter
  */
 export async function update(id: string, data: UpdateMeterInput): Promise<Meter | null> {
+  // If concentrator_id is being updated and project_id is not provided,
+  // automatically get project_id from the new concentrator
+  if (data.concentrator_id !== undefined && data.project_id === undefined) {
+    const concentratorQuery = await query<{ project_id: string }>(
+      'SELECT project_id FROM concentrators WHERE id = $1',
+      [data.concentrator_id]
+    );
+    
+    if (concentratorQuery.rows.length > 0) {
+      data.project_id = concentratorQuery.rows[0].project_id;
+    }
+  }
+
   const updates: string[] = [];
   const params: unknown[] = [];
   let paramIndex = 1;
diff --git a/water-api/src/validators/meter.validator.ts b/water-api/src/validators/meter.validator.ts
index 8ccfd75..5169fdf 100644
--- a/water-api/src/validators/meter.validator.ts
+++ b/water-api/src/validators/meter.validator.ts
@@ -52,8 +52,9 @@ export const createMeterSchema = z.object({
     .min(1, 'Name cannot be empty')
     .max(255, 'Name must be at most 255 characters'),
   project_id: z
-    .string({ required_error: 'Project ID is required' })
-    .regex(uuidRegex, 'Project ID must be a valid UUID'),
+    .string()
+    .regex(uuidRegex, 'Project ID must be a valid UUID')
+    .optional(),  // Optional - will be obtained from concentrator if not provided
   concentrator_id: z
     .string({ required_error: 'Concentrator ID is required' })
     .regex(uuidRegex, 'Concentrator ID must be a valid UUID'),