diff --git a/ingestion-sink/src/main/java/com/mozilla/telemetry/ingestion/sink/config/SinkConfig.java b/ingestion-sink/src/main/java/com/mozilla/telemetry/ingestion/sink/config/SinkConfig.java
index 5a34896f0..59f6563fb 100644
--- a/ingestion-sink/src/main/java/com/mozilla/telemetry/ingestion/sink/config/SinkConfig.java
+++ b/ingestion-sink/src/main/java/com/mozilla/telemetry/ingestion/sink/config/SinkConfig.java
@@ -41,6 +41,7 @@ public class SinkConfig {
   private static final String BATCH_MAX_DELAY = "BATCH_MAX_DELAY";
   private static final String BATCH_MAX_MESSAGES = "BATCH_MAX_MESSAGES";
   private static final String BIG_QUERY_OUTPUT_MODE = "BIG_QUERY_OUTPUT_MODE";
+  private static final String BIG_QUERY_DEFAULT_PROJECT = "BIG_QUERY_DEFAULT_PROJECT";
   private static final String LOAD_MAX_BYTES = "LOAD_MAX_BYTES";
   private static final String LOAD_MAX_DELAY = "LOAD_MAX_DELAY";
   private static final String LOAD_MAX_FILES = "LOAD_MAX_FILES";
@@ -60,11 +61,11 @@ public class SinkConfig {
 
   private static final Set<String> INCLUDE_ENV_VARS = ImmutableSet.of(INPUT_COMPRESSION,
       INPUT_PARALLELISM, INPUT_SUBSCRIPTION, BATCH_MAX_BYTES, BATCH_MAX_DELAY, BATCH_MAX_MESSAGES,
-      BIG_QUERY_OUTPUT_MODE, LOAD_MAX_BYTES, LOAD_MAX_DELAY, LOAD_MAX_FILES, OUTPUT_BUCKET,
-      OUTPUT_COMPRESSION, OUTPUT_FORMAT, OUTPUT_PARALLELISM, OUTPUT_TABLE, OUTPUT_TOPIC,
-      MAX_OUTSTANDING_ELEMENT_COUNT, MAX_OUTSTANDING_REQUEST_BYTES, SCHEMAS_LOCATION,
-      STREAMING_BATCH_MAX_BYTES, STREAMING_BATCH_MAX_DELAY, STREAMING_BATCH_MAX_MESSAGES,
-      STREAMING_DOCTYPES, STRICT_SCHEMA_DOCTYPES);
+      BIG_QUERY_OUTPUT_MODE, BIG_QUERY_DEFAULT_PROJECT, LOAD_MAX_BYTES, LOAD_MAX_DELAY,
+      LOAD_MAX_FILES, OUTPUT_BUCKET, OUTPUT_COMPRESSION, OUTPUT_FORMAT, OUTPUT_PARALLELISM,
+      OUTPUT_TABLE, OUTPUT_TOPIC, MAX_OUTSTANDING_ELEMENT_COUNT, MAX_OUTSTANDING_REQUEST_BYTES,
+      SCHEMAS_LOCATION, STREAMING_BATCH_MAX_BYTES, STREAMING_BATCH_MAX_DELAY,
+      STREAMING_BATCH_MAX_MESSAGES, STREAMING_DOCTYPES, STRICT_SCHEMA_DOCTYPES);
 
   // BigQuery.Write.Batch.getByteSize reports protobuf size, which can be ~1/3rd more
   // efficient than the JSON that actually gets sent over HTTP, so we use to 60% of the
@@ -386,8 +387,11 @@ private static String getBigQueryOutputBucket(Env env) {
     return getGcsOutputBucket(env) + OUTPUT_TABLE + "=" + env.getString(OUTPUT_TABLE) + "/";
   }
 
-  private static com.google.cloud.bigquery.BigQuery getBigQueryService(Env env) {
-    return BigQueryOptions.getDefaultInstance().getService();
+  @VisibleForTesting
+  static com.google.cloud.bigquery.BigQuery getBigQueryService(Env env) {
+    BigQueryOptions.Builder builder = BigQueryOptions.getDefaultInstance().toBuilder();
+    env.optString(BIG_QUERY_DEFAULT_PROJECT).ifPresent(builder::setProjectId);
+    return builder.build().getService();
   }
 
   private static Storage getGcsService(Env env) {
diff --git a/ingestion-sink/src/main/java/com/mozilla/telemetry/ingestion/sink/util/Env.java b/ingestion-sink/src/main/java/com/mozilla/telemetry/ingestion/sink/util/Env.java
index 620bddb6c..b7026dffd 100644
--- a/ingestion-sink/src/main/java/com/mozilla/telemetry/ingestion/sink/util/Env.java
+++ b/ingestion-sink/src/main/java/com/mozilla/telemetry/ingestion/sink/util/Env.java
@@ -38,7 +38,8 @@ public boolean containsKey(String key) {
     return env.containsKey(key);
   }
 
-  private Optional<String> optString(String key) {
+  /** Get the value of an optional environment variable. */
+  public Optional<String> optString(String key) {
     if (!include.contains(key)) {
       throw new IllegalArgumentException("key missing from include: " + key);
     }
diff --git a/ingestion-sink/src/test/java/com/mozilla/telemetry/ingestion/sink/config/SinkConfigTest.java b/ingestion-sink/src/test/java/com/mozilla/telemetry/ingestion/sink/config/SinkConfigTest.java
new file mode 100644
index 000000000..dc630010c
--- /dev/null
+++ b/ingestion-sink/src/test/java/com/mozilla/telemetry/ingestion/sink/config/SinkConfigTest.java
@@ -0,0 +1,25 @@
+package com.mozilla.telemetry.ingestion.sink.config;
+
+import static org.junit.Assert.assertEquals;
+
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.common.collect.ImmutableSet;
+import com.mozilla.telemetry.ingestion.sink.util.Env;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.contrib.java.lang.system.EnvironmentVariables;
+
+public class SinkConfigTest {
+
+  @Rule
+  public final EnvironmentVariables environmentVariables = new EnvironmentVariables();
+
+  @Test
+  public void canDetectBqProject() {
+    environmentVariables.set("GOOGLE_CLOUD_PROJECT", "gcp-project");
+    environmentVariables.set("BIG_QUERY_DEFAULT_PROJECT", "bq-project");
+    Env env = new Env(ImmutableSet.of("BIG_QUERY_DEFAULT_PROJECT"));
+    assertEquals("gcp-project", BigQueryOptions.getDefaultInstance().getProjectId());
+    assertEquals("bq-project", SinkConfig.getBigQueryService(env).getOptions().getProjectId());
+  }
+}